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Sample records for cast duplex stainless

  1. Phase Transformations in Cast Duplex Stainless Steels

    SciTech Connect

    Kim, Yoon-Jun

    2004-01-01

    Duplex stainless steels (DSS) constitute both ferrite and austenite as a matrix. Such a microstructure confers a high corrosion resistance with favorable mechanical properties. However, intermetallic phases such as σ and χ can also form during casting or high-temperature processing and can degrade the properties of the DSS. This research was initiated to develop time-temperature-transformation (TTT) and continuous-cooling-transformation (CCT) diagrams of two types of cast duplex stainless steels, CD3MN (Fe-22Cr-5Ni-Mo-N) and CD3MWCuN (Fe-25Cr-7Ni-Mo-W-Cu-N), in order to understand the time and temperature ranges for intermetallic phase formation. The alloys were heat treated isothermally or under controlled cooling conditions and then characterized using conventional metallographic methods that included tint etching, and also using electron microscopy (SEM, TEM) and wavelength dispersive spectroscopy (WDS). The kinetics of intermetallic-phase (σ + χ) formation were analyzed using the Johnson-Mehl-Avrami (MA) equation in the case of isothermal transformations and a modified form of this equation in the case of continuous cooling transformations. The rate of intermetallic-phase formation was found to be much faster in CD3MWCuN than CD3MN due mainly to differences in the major alloying contents such as Cr, Ni and Mo. To examine in more detail the effects of these elements of the phase stabilities; a series of eight steel castings was designed with the Cr, Ni and Mo contents systematically varied with respect to the nominal composition of CD3MN. The effects of varying the contents of alloying additions on the formation of intermetallic phases were also studied computationally using the commercial thermodynamic software package, Thermo-Calc. In general, σ was stabilized with increasing Cr addition and χ by increasing Mo addition. However, a delicate balance among Ni and other minor elements such as N and Si also exists. Phase equilibria in DSS can be affected by

  2. Use of duplex stainless steel castings in control valves

    SciTech Connect

    Gossett, J.L.

    1996-07-01

    Duplex stainless steels have enjoyed rapidly increasing popularity in recent years. For numerous reasons the availability of these alloys in the cast form has lagged behind the availability of the wrought form. Commercial demand for control valves in these alloys has driven development of needed information to move into production. A systematic approach was used to develop specifications, suppliers and weld procedures. Corrosion, stress corrosion cracking (SCC), sulfide stress cracking (SSC) and hardness results are also presented for several alloys including; CD3MN (UNS J92205), CD4MCu (UNS J93370) and CD7MCuN (cast UNS S32550).

  3. Thermal Aging Phenomena in Cast Duplex Stainless Steels

    NASA Astrophysics Data System (ADS)

    Byun, T. S.; Yang, Y.; Overman, N. R.; Busby, J. T.

    2016-02-01

    Cast stainless steels (CASSs) have been extensively used for the large components of light water reactor (LWR) power plants such as primary coolant piping and pump casing. The thermal embrittlement of CASS components is one of the most serious concerns related to the extended-term operation of nuclear power plants. Many past researches have concluded that the formation of Cr-rich α'-phase by Spinodal decomposition of δ-ferrite phase is the primary mechanism for the thermal embrittlement. Cracking mechanism in the thermally-embrittled duplex stainless steels consists of the formation of cleavage at ferrite and its propagation via separation of ferrite-austenite interphase. This article intends to provide an introductory overview on the thermal aging phenomena in LWR-relevant conditions. Firstly, the thermal aging effect on toughness is discussed in terms of the cause of embrittlement and influential parameters. An approximate analysis of thermal reaction using Arrhenius equation was carried out to scope the aging temperatures for the accelerated aging experiments to simulate the 60 and 80 years of services. Further, an equilibrium precipitation calculation was performed for model CASS alloys using the CALPHAD program, and the results are used to describe the precipitation behaviors in duplex stainless steels. These results are also to be used to guide an on-going research aiming to provide knowledge-based conclusive prediction for the integrity of the CASS components of LWR power plants during the service life extended up to and beyond 60 years.

  4. Thermal Aging Phenomena in Cast Duplex Stainless Steels

    SciTech Connect

    Byun, T. S.; Yang, Y.; Overman, N. R.; Busby, J. T.

    2015-11-12

    We used cast stainless steels (CASSs)for the large components of light water reactor (LWR) power plants such as primary coolant piping and pump casing. The thermal embrittlement of CASS components is one of the most serious concerns related to the extended-term operation of nuclear power plants. Many past researches have concluded that the formation of Cr-rich alpha-phase by Spinodal decomposition of delta-ferrite phase is the primary mechanism for the thermal embrittlement. Cracking mechanism in the thermally-embrittled duplex stainless steels consists of the formation of cleavage at ferrite and its propagation via separation of ferrite-austenite interphase. This article intends to provide an introductory overview on the thermal aging phenomena in LWR-relevant conditions. Firstly, the thermal aging effect on toughness is discussed in terms of the cause of embrittlement and influential parameters. Moreover, an approximate analysis of thermal reaction using Arrhenius equation was carried out to scope the aging temperatures for the accelerated aging experiments to simulate the 60 and 80 years of services. Further, an equilibrium precipitation calculation was performed for model CASS alloys using the CALPHAD program, and the results are used to describe the precipitation behaviors in duplex stainless steels. Our results are also to be used to guide an on-going research aiming to provide knowledge-based conclusive prediction for the integrity of the CASS components of LWR power plants during the service life extended up to and beyond 60 years.

  5. Thermal Aging Phenomena in Cast Duplex Stainless Steels

    DOE PAGES

    Byun, T. S.; Yang, Y.; Overman, N. R.; Busby, J. T.

    2015-11-12

    We used cast stainless steels (CASSs)for the large components of light water reactor (LWR) power plants such as primary coolant piping and pump casing. The thermal embrittlement of CASS components is one of the most serious concerns related to the extended-term operation of nuclear power plants. Many past researches have concluded that the formation of Cr-rich alpha-phase by Spinodal decomposition of delta-ferrite phase is the primary mechanism for the thermal embrittlement. Cracking mechanism in the thermally-embrittled duplex stainless steels consists of the formation of cleavage at ferrite and its propagation via separation of ferrite-austenite interphase. This article intends to providemore » an introductory overview on the thermal aging phenomena in LWR-relevant conditions. Firstly, the thermal aging effect on toughness is discussed in terms of the cause of embrittlement and influential parameters. Moreover, an approximate analysis of thermal reaction using Arrhenius equation was carried out to scope the aging temperatures for the accelerated aging experiments to simulate the 60 and 80 years of services. Further, an equilibrium precipitation calculation was performed for model CASS alloys using the CALPHAD program, and the results are used to describe the precipitation behaviors in duplex stainless steels. Our results are also to be used to guide an on-going research aiming to provide knowledge-based conclusive prediction for the integrity of the CASS components of LWR power plants during the service life extended up to and beyond 60 years.« less

  6. Final Report, Volume 1, Metallurgical Evaluation of Cast Duplex Stainless Steels and their Weldments

    SciTech Connect

    Wen, Songqing; Lundin, Carl, W.; Batten, Greg, W.

    2005-09-30

    Duplex stainless steels (DSS) are being specified for chloride containing environments due to their enhanced pitting and stress corrosion cracking resistance. They exhibit improved corrosion performance over the austenitic stainless steels. Duplex stainless steels also offer improved strength properties and are available in various wrought and cast forms. Selected grades of duplex stainless steel castings and their welds, in comparison with their wrought counterparts, were evaluated, regarding corrosion performance and mechanical properties and weldability. Multiple heats of cast duplex stainless steel were evaluated in the as-cast, solution annealed (SA) static cast and SA centrifugal cast conditions, while their wrought counterparts were characterized in the SA condition and in the form of as-rolled plate. Welding, including extensive assessment of autogenous welds and a preliminary study of composite welds (shielded metal arc weld (SMAW)), was performed. The evaluations included critical pitting temperature (CPT) testing, intergranular corrosion (IGC) testing, ASTM A923 (Methods A, B and C), Charpy impact testing, weldability testing (ASTM A494), ferrite measurement and microstructural evaluations. In the study, the corrosion performances of DSS castings were characterized and assessed, including the wrought counterparts for comparison. The evaluation filled the pore of lack of data for cast duplex stainless steels compared to wrought materials. A database of the pitting corrosion and IGC behavior of cast and wrought materials was generated for a greater depth of understanding for the behavior of cast duplex stainless steel. In addition, improved evaluation methods for DSS castings were developed according to ASTM A923, A262, G48 and A494. The study revealed that when properly heat treated according to the specification, (1) DSS castings have equal or better pitting and intergranular corrosion resistance than their wrought counterparts; (2) Welding reduces the

  7. Final Report, Volume 1, Metallurgical Evaluation of Cast Duplex Stainless Steels and their Weldments

    SciTech Connect

    Wen, Songqing; Lundin, Carl, W.; Batten, Greg, W.

    2005-09-30

    Duplex stainless steels (DSS) are being specified for chloride containing environments due to their enhanced pitting and stress corrosion cracking resistance. They exhibit improved corrosion performance over the austenitic stainless steels. Duplex stainless steels also offer improved strength properties and are available in various wrought and cast forms. Selected grades of duplex stainless steel castings and their welds, in comparison with their wrought counterparts, were evaluated, regarding corrosion performance and mechanical properties and weldability. Multiple heats of cast duplex stainless steel were evaluated in the as-cast, solution annealed (SA) static cast and SA centrifugal cast conditions, while their wrought counterparts were characterized in the SA condition and in the form of as-rolled plate. Welding, including extensive assessment of autogenous welds and a preliminary study of composite welds (shielded metal arc weld (SMAW)), was performed. The evaluations included critical pitting temperature (CPT) testing, intergranular corrosion (IGC) testing, ASTM A923 (Methods A, B and C), Charpy impact testing, weldability testing (ASTM A494), ferrite measurement and microstructural evaluations. In the study, the corrosion performances of DSS castings were characterized and assessed, including the wrought counterparts for comparison. The evaluation filled the pore of lack of data for cast duplex stainless steels compared to wrought materials. A database of the pitting corrosion and IGC behavior of cast and wrought materials was generated for a greater depth of understanding for the behavior of cast duplex stainless steel. In addition, improved evaluation methods for DSS castings were developed according to ASTM A923, A262, G48 and A494. The study revealed that when properly heat treated according to the specification, (1) DSS castings have equal or better pitting and intergranular corrosion resistance than their wrought counterparts; (2) Welding reduces the

  8. Final Report, Volume 3, Guidance Document for the Evaluation of Cast Super Duplex Stainless Steel

    SciTech Connect

    Hariharan, Vasudevan; Lundin, Carl, D.

    2005-09-30

    Volume 3 comprises of the Development of Qualification Standards for Cast Super Duplex Stainless Steel (A890-5A) which is equivalent to wrought 2507. The objective of this work was to determine the suitability of ASTM A923 Standard Test methods for Detecting Detrimental Intermetallic Phase in Duplex Austenitic-Ferritic Stainless Steels for 25 Cr Cast Super Duplex Stainless Steels (ASTM A890-5A). The various tests which were carried out were ASTM A923 Test Method A, B and C (Sodium Hydroxide Etch Test, Charpy Impact Test and Ferric Chloride Corrosion Test), ferrite measurement using Feritscope{reg_sign}, ASTM E562 Manual Point Count Method and X-Ray Diffraction, hardness measurement using Rockwell B and C and microstructural analysis using SEM and EDS.

  9. Final Report, Volume 3, Guidance Document for the Evaluation of Cast Super Duplex Stainless Steel

    SciTech Connect

    Hariharan, Vasudevan; Lundin, Carl, W.

    2005-09-30

    Volume 3 is comprised of the Development of Qualification Standards for Cast Super Duplex Stainless Steel (A890-5A) which is equivalent to wrought 2507. The objective of this work was to determine the suitability of ASTM A923 Standard Test methods for Detecting Detrimental Intermetallic Phase in Duplex Austenitic-Ferritic Stainless Steels for 25 Cr Cast Super Duplex Stainless Steels (ASTM A890-5A). The various tests which were carried out were ASTM A923 Test Method A, B and C (Sodium Hydroxide Etch Test, Charpy Impact Test and Ferric Chloride Corrosion Test), ferrite measurement using Feritscope®, ASTM E562 Manual Point Count Method and X-Ray Diffraction, hardness measurement using Rockwell B and C and microstructural analysis using SEM and EDS.

  10. Ferrite Measurement in Austenitic and Duplex Stainless Steel Castings - Final Report

    SciTech Connect

    Lundin, C.D.; Zhou, G.; Ruprecht, W.

    1999-08-01

    The ability to determine ferrite rapidly, accurately and directly on a finished casting, in the solution annealed condition, can enhance the acceptance, save on manufacturing costs and ultimately improve service performance of duplex stainless steel cast products. If the suitability of a non-destructive ferrite determination methodology can be demonstrated for standard industrial measurement instruments, the production of cast secondary standards for calibration of these instruments is a necessity. With these concepts in mind, a series of experiments were carried out to demonstrate, in a non-destructive manner, the proper methodology for determining ferrite content. The literature was reviewed, with regard to measurement techniques and vagaries, an industrial ferrite measurement round-robin was conducted, the effects of casting surface finish, preparation of the casting surface for accurate measurement and the evaluation of suitable means for the production of cast secondary standards for calibration were systematically investigated. The data obtained from this research program provide recommendations to ensure accurate, repeatable, and reproducible ferrite measurement and qualifies the Feritscope for field use on production castings.

  11. Ferrite Measurement in Austenitic and Duplex Stainless Steel Castings - Literature Review

    SciTech Connect

    Lundin, C.D.; Zhou, G.; Ruprecht, W.

    1999-08-01

    The ability to determine ferrite rapidly, accurately and directly on a finished casting, in the solution annealed condition, can enhance the acceptance, save on manufacturing costs and ultimately improve service performance of duplex stainless steel cast products. If the suitability of a non-destructive ferrite determination methodology can be demonstrated for standard industrial measurement instruments, the production of cast secondary standards for calibration of these instruments is a necessity. With these concepts in mind, a series of experiments were carried out to demonstrate, in a non-destructive manner, the proper methodology for determining ferrite content. The literature was reviewed, with regard to measurement techniques and vagaries, an industrial ferrite measurement round-robin was conducted, the effects of casting surface finish, preparation of the casting surface for accurate measurement and the evaluation of suitable means for the production of cast secondary standards for calibration were systematically investigated. The data obtained from this research program provides recommendations to insure accurate, repeatable and reproducible ferrite measurement and qualifies the Feritscope for field use on production castings.

  12. Clean cast steel technology. Determination of transformation diagrams for duplex stainless steel

    SciTech Connect

    Chumbley, S. L.

    2005-09-01

    Duplex stainless steels (DSS) constitute both ferrite and austenite as a matrix. Such a microstructure confers a high corrosion resistance with favorable mechanical properties. However, intermetallic phases such as sigma ( can also form during casting or high-temperature processing and can degrade the properties of the DSS. This research was initiated to develop time-temperature-transformation (TTT) and continuous-cooling- transformation (CCT) diagrams of two types of cast duplex stainless steels, CD3MN (Fe 22Cr-5Ni-Mo-N) and CD3MWCuN (Fe-25Cr-7Ni-Mo-W-Cu-N), in order to understand the time and temperature ranges for intermetallic phase formation. The alloys were heat treated isothermally or under controlled cooling conditions and then characterized using conventional metallographic methods that included tint etching, and also using electron microscopy (SEM, TEM) and wavelength dispersive spectroscopy (WDS). The kinetics of intermetallic-phase ( formation were analyzed using the Johnson-Mehl-Avrami (JMA) equation in the case of isothermal transformations and a modified form of this equation in the case of continuous cooling transformations, The rate of intermetallic-phase formation was found to be much faster in CD3MWCuN than CD3MN due mainly to differences in the major alloying contents such as Cr, Ni and Mo. To examine in more detail the effects of these elements of the phase stabilities, a series of eight steel castings was designed with the Cr, Ni and Mo contents systematically varied with respect to the nominal composition of CD3MN. The effects of varying the contents of alloying additions on the formation of intermetallic phases were also studied computationally using the commercial thermodynamic software package, Thermo-Calc. In general, was stabilized with increasing Cr addition and by increasing Mo addition. However, a delicate balance among Ni and other minor elements such as N and Si also exists. Phase equilibria in DSS can be affected by local

  13. Microstructural characteristics and corrosion behavior of a super duplex stainless steel casting

    SciTech Connect

    Martins, Marcelo Casteletti, Luiz Carlos

    2009-02-15

    The machining of super duplex stainless steel castings is usually complicated by the difficulty involved in maintaining the dimensional tolerances required for given applications. Internal stresses originating from the solidification process and from subsequent heat treatments reach levels that exceed the material's yield strength, promoting plastic strain. Stress relief heat treatments at 520 deg. C for 2 h are an interesting option to solve this problem, but because these materials present a thermodynamically metastable condition, a few precautions should be taken. The main objective of this work was to demonstrate that, after solution annealing at 1130 deg. C and water quenching, stress relief at 520 deg. C for 2 h did not alter the duplex microstructure or impair the pitting corrosion resistance of ASTM A890/A890M Grade 6A steel. This finding was confirmed by microstructural characterization techniques, including light optical and scanning electron microscopy, and X-ray diffraction. Corrosion potential measurements in synthetic sea water containing 20,000 ppm of chloride ions were also conducted at three temperatures: 5 deg. C, 25 deg. C and 60 deg. C.

  14. Final Report, Volume 2, The Development of Qualification Standards for Cast Duplex Stainless Steel

    SciTech Connect

    Russell, Steven, W.; Lundin, Carl, D.

    2005-09-30

    The scope of testing cast Duplex Stainless Steel (DSS) required testing to several ASTM specifications, while formulating and conducting industry round robin tests to verify and study the reproducibility of the results. ASTM E562 (Standard Test Method for Determining Volume Fraction by Systematic manual Point Count) and ASTM A923 (Standard Test Methods for Detecting Detrimental Intermetallic Phase in Wrought Duplex Austenitic/Ferritic Stainless Steels) were the specifications utilized in conducting this work. An ASTM E562 industry round robin, ASTM A923 applicability study, ASTM A923 industry round robin, and an ASTM A923 study of the effectiveness of existing foundry solution annealing procedures for producing cast DSS without intermetallic phases were implemented. In the ASTM E562 study, 5 samples were extracted from various cast austenitic and DSS in order to have varying amounts of ferrite. Each sample was metallographically prepared by UT and sent to each of 8 participants for volume fraction of ferrite measurements. Volume fraction of ferrite was measured using manual point count per ASTM E562. FN was measured from the Feritescope{reg_sign} and converted to volume fraction of ferrite. Results indicate that ASTM E562 is applicable to DSS and the results have excellent lab-to-lab reproducibility. Also, volume fraction of ferrite conversions from the FN measured by the Feritescope{reg_sign} were similar to volume fraction of ferrite measured per ASTM E562. In the ASTM A923 applicability to cast DSS study, 8 different heat treatments were performed on 3 lots of ASTM A890-4A (CD3MN) castings and 1 lot of 2205 wrought DSS. The heat treatments were selected to produce a wide range of cooling rates and hold times in order to study the suitability of ASTM A923 to the response of varying amounts on intermetallic phases [117]. The test parameters were identical to those used to develop ASTM A923 for wrought DSS. Charpy V-notch impact samples were extracted from the

  15. Final Report, Volume 2, The Development of Qualification Standards for Cast Duplex Stainless Steel

    SciTech Connect

    Russell, Steven, W.; Lundin, Carl, W.

    2005-09-30

    The scope of testing cast Duplex Stainless Steel (DSS) required testing to several ASTM specifications, while formulating and conducting industry round robin tests to verify and study the reproducibility of the results. ASTM E562 (Standard Test Method for Determining Volume Fraction by Systematic manual Point Count) and ASTM A923 (Standard Test Methods for Detecting Detrimental Intermetallic Phase in Wrought Duplex Austenitic/Ferritic Stainless Steels) were the specifications utilized in conducting this work. An ASTM E562 industry round robin, ASTM A923 applicability study, ASTM A923 industry round robin, and an ASTM A923 study of the effectiveness of existing foundry solution annealing procedures for producing cast DSS without intermetallic phases were implemented. In the ASTM E562 study, 5 samples were extracted from various cast austenitic and DSS in order to have varying amounts of ferrite. Each sample was metallographically prepared by UT and sent to each of 8 participants for volume fraction of ferrite measurements. Volume fraction of ferrite was measured using manual point count per ASTM E562. FN was measured from the Feritescope® and converted to volume fraction of ferrite. Results indicate that ASTM E562 is applicable to DSS and the results have excellent lab-to-lab reproducibility. Also, volume fraction of ferrite conversions from the FN measured by the Feritescope® were similar to volume fraction of ferrite measured per ASTM E562. In the ASTM A923 applicability to cast DSS study, 8 different heat treatments were performed on 3 lots of ASTM A890-4A (CD3MN) castings and 1 lot of 2205 wrought DSS. The heat treatments were selected to produce a wide range of cooling rates and hold times in order to study the suitability of ASTM A923 to the response of varying amounts on intermetallic phases [117]. The test parameters were identical to those used to develop ASTM A923 for wrought DSS. Charpy V-notch impact samples were extracted from the castings and wrought

  16. Erosive Wear Behavior of High-Alloy Cast Iron and Duplex Stainless Steel under Mining Conditions

    NASA Astrophysics Data System (ADS)

    Yoganandh, J.; Natarajan, S.; Kumaresh Babu, S. P.

    2015-09-01

    Centrifugal pumps used in the lignite mines encounter erosive wear problems, leading to a disastrous failure of the pump casings. This paper attempts to evaluate the erosive wear resistance of Ni-Hard 4, high-chromium iron, and Cast CD4MCu duplex stainless steel (DSS), for mining conditions. The prepared test coupons were subjected to an erosion test by varying the impingement velocity and the angle of impingement, under two different pH conditions of 3 and 7, which pertained to the mining conditions. XRD analysis was carried out to confirm the phases present in the alloy. The eroded surface was subjected to SEM analysis to identify the erosion mechanisms. The surface degradation of Ni-Hard 4 and high-chromium iron came from a low-angle abrasion with a grooving and plowing mechanism at a low angle of impingement. At normal impingement, deep indentations resulted in lips and crater formations, leading to degradation of the surface in a brittle manner. A combined extrusion-forging mechanism is observed in the CD4MCu DSS surface at all the impingement angles.

  17. Sigma phase morphologies in cast and aged super duplex stainless steel

    SciTech Connect

    Martins, Marcelo; Casteletti, Luiz Carlos

    2009-08-15

    Solution annealed and water quenched duplex and super duplex stainless steels are thermodynamically metastable systems at room temperature. These systems do not migrate spontaneously to a thermodynamically stable condition because an energy barrier separates the metastable and stable states. However, any heat input they receive, for example through isothermal treatment or through prolonged exposure to a voltaic arc in the welding process, cause them to reach a condition of stable equilibrium which, for super duplex stainless steels, means precipitation of intermetallic and carbide phases. These phases include the sigma phase, which is easily identified from its morphology, and its influence on the material's impact strength. The purpose of this work was to ascertain how 2-hour isothermal heat treatments at 920 deg. C and 980 deg. C affect the microstructure of ASTM A890/A890M GR 6A super duplex stainless steel. The sigma phase morphologies were found to be influenced by these two aging temperatures, with the material showing a predominantly lacy microstructure when heat treated at 920 deg. C and block-shaped when heat treated at 980 deg. C.

  18. Development of TRIP-Aided Lean Duplex Stainless Steel by Twin-Roll Strip Casting and Its Deformation Mechanism

    NASA Astrophysics Data System (ADS)

    Zhao, Yan; Zhang, Weina; Liu, Xin; Liu, Zhenyu; Wang, Guodong

    2016-10-01

    In the present work, twin-roll strip casting was carried out to fabricate thin strip of a Mn-N alloyed lean duplex stainless steel with the composition of Fe-19Cr-6Mn-0.4N, in which internal pore defects had been effectively avoided as compared to conventional cast ingots. The solidification structure observed by optical microscope indicated that fine Widmannstatten structure and coarse-equiaxed crystals had been formed in the surface and center, respectively, with no columnar crystal structures through the surface to center of the cast strip. By applying hot rolling and cold rolling, thin sheets with the thickness of 0.5 mm were fabricated from the cast strips, and no edge cracks were formed during the rolling processes. With an annealing treatment at 1323 K (1050 °C) for 5 minutes after cold rolling, the volume fractions of ferrite and austenite were measured to be approximately equal, and the distribution of alloying elements in the strip was further homogenized. The cold-rolled and annealed sheet exhibited an excellent combination of strength and ductility, with the ultimate tensile strength and elongation having been measured to be 1000 MPa and 65 pct, respectively. The microstructural evolution during deformation was investigated by XRD, EBSD, and TEM, indicating that ferrite and austenite had different deformation mechanisms. The deformation of ferrite phase was dominated by dislocation slipping, and the deformation of austenite phase was mainly controlled by martensitic transformation in the sequence of γ→ɛ-martensite→α'-martensite, leading to the improvement of strength and plasticity by the so-called transformation-induced plasticity (TRIP) effect. By contrast, lean duplex stainless steels of Fe-21Cr-6Mn-0.5N and Fe-23Cr-7Mn-0.6N fabricated by twin-roll strip casting did not show TRIP effects and exhibited lower strength and elongation as compared to Fe-19Cr-6Mn-0.4N.

  19. Final Report, Volume 4, The Develpoment of Qualification Standards forCast Super Duplex Stainless Steel (2507 Wrought Equivalent)

    SciTech Connect

    Hariharan, Vasudevan; Lundin, Carl, D.

    2005-09-30

    The objective of the program is to determine the suitability of ASTM A923 Standard Test methods for Detecting Detrimental Intermetallic Phase in Wrought Duplex Austenitic-Ferritic Stainless Steels for 25 Cr Cast Super Duplex Stainless Steels (ASTM A890-5A). Different tests were carried out on the materials procured from various steel foundries as stated in the ASTM A923. The foundries were designated as Foundry A, B, C and D. All the materials were foundry solution annealed. Materials from Foundry D were solution heat treated at The University of Tennessee also and then they were subjected to heat treatment schedule which was derived from the testing of wrought DSS to establish the A923 specification. This was possible because the material from the same heat was sufficient for conducting the full scope of heat treatment. This was done prior to carrying out various other tests. Charpy samples were machined. The Ferrite content was measured in all the Charpy samples using Feritscope{reg_sign} and ASTM E562 Manual Point Count Method. After the ferrite content was measured the samples were sent to AMC-Vulcan, Inc. in Alabama to conduct the Charpy impact test based on ASTM A923 Test Method B. This was followed by etch testing and corrosion analysis based on ASTM A923 Test Methods A and C respectively at University of Tennessee. Hardness testing using Rockwell B and C was also carried out on these samples. A correlation was derived between all the three test methods and the best method for evaluating the presence of intermetallic in the material was determined. The ferrite content was correlated with the toughness values. Microstructural analysis was carried out on the etch test samples using Scanning Electron Microscopy in order to determine if intermetallic phases were present. The fracture surfaces from Charpy test specimens were also observed under SEM in order to determine the presence of any cracks and whether it was a brittle or a ductile fracture. A correlation

  20. Final Report, Volume 4, The Development of Qualification Standards for Cast Super Duplex Stainless Steel (2507 Wrought Equivalent)

    SciTech Connect

    Hariharan, Vasudevan; Lundin, Carl, W.

    2005-09-30

    The objective of the program is to determine the suitability of ASTM A923 Standard Test methods for Detecting Detrimental Intermetallic Phase in Wrought Duplex Austenitic-Ferritic Stainless Steels for 25 Cr Cast Super Duplex Stainless Steels (ASTM A890-5A). Different tests were carried out on the materials procured from various steel foundries as stated in the ASTM A923. The foundries were designated as Foundry A, B, C and D. All the materials were foundry solution annealed. Materials from Foundry D were solution heat treated at The University of Tennessee also and then they were subjected to heat treatment schedule which was derived from the testing of wrought DSS to establish the A923 specification. This was possible because the material from the same heat was sufficient for conducting the full scope of heat treatment. This was done prior to carrying out various other tests. Charpy samples were machined. The Ferrite content was measured in all the Charpy samples using Feritscope® and ASTM E562 Manual Point Count Method. After the ferrite content was measured the samples were sent to AMC-Vulcan, Inc. in Alabama to conduct the Charpy impact test based on ASTM A923 Test Method B. This was followed by etch testing and corrosion analysis based on ASTM A923 Test Methods A and C respectively at University of Tennessee. Hardness testing using Rockwell B and C was also carried out on these samples. A correlation was derived between all the three test methods and the best method for evaluating the presence of intermetallic in the material was determined. The ferrite content was correlated with the toughness values. Microstructural analysis was carried out on the etch test samples using Scanning Electron Microscopy in order to determine if intermetallic phases were present. The fracture surfaces from Charpy test specimens were also observed under SEM in order to determine the presence of any cracks and whether it was a brittle or a ductile fracture. A correlation was

  1. Long-term embrittlement of cast duplex stainless steels in LWR systems. Semiannual report, October 1991--March 1992: Volume 7, No.1

    SciTech Connect

    Chopra, O.K.

    1993-05-01

    This progress report summarizes work performed by Argonne National Laboratory on long-term thermal embrittlement of cast duplex stainless steels in LWR systems during the six months from October 1991 to March 1992. Charpy-impact, tensile, and fracture toughness J-R curve data are presented for several heats of cast stainless steel that were aged 10,000-58,000 h at 290, 320, and 350{degree}C. The results indicate that thermal aging decreases the fracture toughness of cast stainless steels. In general, CF-3 steels are the least sensitive to thermal aging and CF-8M steels are the most sensitive. The values of fracture toughness J{sub IC} and tearing modulus for CF-8M steels can be as low as {approx}90 kJ/m{sup 2} and {approx}60, respectively. The fracture toughness data are consistent with the Charpy-impact results, i.e. unaged and aged steels that show low impact energy also exhibit lower fracture toughness. All steels reach a minimum saturation fracture toughness after thermal aging; the time to reach saturation depends on the aging temperature. The results also indicate that low-strength cast stainless steels are generally insensitive to thermal aging.

  2. Final Report, Volume 5, Data Package for ASTM A923 Supporting Inclusion of A890-5 Super Duplex Stainless Steel (Cast Equivalent of 2507)

    SciTech Connect

    Hariharan, Vasudevan; Lundin, Carl, W.

    2005-09-30

    Volume 5 is the Data Package for the evaluation of Super Duplex Stainless Steel Castings prepared at the end of work comprised in volumes 3 and 4. The document deals with the various evaluation methods used in the work documented in volume 3 and 4. This document covers materials regarding evaluation of the A890-5A material in terms of inclusion in ASTM A923. The various tests which were conducted on the A890-5A material are included in this document.

  3. Final Report, Volume 5, Data Package for ASTM A923 Supporting Inclusion of A890-5A Super Duplex Stainless Steel ( Cast Equivalent of 2507)

    SciTech Connect

    Hariharan, Vasudevan; Lundin, Carl, D.

    2005-09-30

    Volume 5 is the Data Package for the evaluation of Super Duplex Stainless Steel Castings prepared at the end of work comprised in volumes 3 and 4. The document deals with the various evaluation methods used in the work documented in volume 3 and 4. This document covers materials regarding evaluation of the A890-5A material in terms of inclusion in ASTM A923. The various tests which were conducted on the A890-5A material are included in this document.

  4. 60 Years of duplex stainless steel applications

    SciTech Connect

    Olsson, J.; Liljas, M.

    1994-12-31

    In this paper the history of wrought duplex stainless steel development and applications is described. Ferritic-austenitic stainless steels were introduced only a few decades after stainless steels were developed. The paper gives details from the first duplex stainless steels in the 1930`s to the super duplex stainless steel development during the 1980`s. During the years much effort has been devoted to production and welding metallurgy as well as corrosion research of the duplex stainless steels. Therefore, duplex stainless steels are to-day established in a wide product range. Numerous important applications are exemplified. In most cases the selection of a duplex steel has been a result of the combination high strength excellent corrosion resistance. In the pulp and paper industry the most interesting use is as vessel material in digesters. For chemical process industry, the duplex steels are currently used in heat exchangers. The largest application of duplex steels exists in the oil and gas/offshore industry. Hundreds of kms of pipelines are installed and are still being installed. An increased use of duplex steels is foreseen in areas where the strength is of prime importance.

  5. Aging degradation of cast stainless steel

    SciTech Connect

    Chopra, O.K.; Chung, H.M.

    1985-10-01

    A program is being conducted to investigate the significance of in-service embrittlement of cast-duplex stainless steels under light-water reactor operating conditions. Data from room-temperature Charpy-impact tests for several heats of cast stainless steel aged up to 10,000 h at 350, 400, and 450/sup 0/C are presented and compared with results from other studies. Microstructures of cast-duplex stainless steels subjected to long-term aging either in the laboratory or in reactor service have been characterized. The results indicate that at least two processes contribute to the low-temperature embrittleent of duplex stainless steels, viz., weakening of the ferrite/austenite phase boundary by carbide precipitation and embrittlement of ferrite matrix by the formation of additional phases such as G-phase, Type X, or the ..cap alpha..' phase. Carbide precipitation has a significant effect on the onset of embrittlement of CF-8 and -8M grades of stainless steels aged at 400 or 450/sup 0/C. The existing correlations do not accurately represent the embrittlement behavior over the temperature range 300 to 450/sup 0/C. 18 refs., 13 figs.

  6. Applications and experiences with super duplex stainless steel in wet FGD scrubber systems

    SciTech Connect

    Francis, R.; Byrne, G.; Warburton, G.; Hebdon, S.

    1998-12-31

    The paper presents the properties of the author`s company`s proprietary super duplex stainless steel. Work is presented showing the development of a more realistic laboratory solution representing typical limestone slurries found in real flue gas desulfurization (FGD) systems. The importance of additions of metal ions such as Fe{sup 3+} and Mn{sup 2+} as well as partially oxidized sulfur species is demonstrated. Results are presented comparing the crevice corrosion resistance of super duplex stainless steel in these slurries with other commonly used wrought and cast stainless steels, for both simulated anthracite and lignite type slurries. Data from loop tests on the erosion resistance of a range of alloys in simulated FGD slurries is presented. The results clearly show the superior resistance of super duplex stainless steel to both crevice corrosion and erosion in FGD slurries. Finally the experiences in UK FGD systems with both cast and wrought super duplex stainless steel are presented.

  7. Heat treatment temperature influence on ASTM A890 GR 6A super duplex stainless steel microstructure

    SciTech Connect

    Martins, Marcelo; E-mail: marcelo.martins@sulzer.com; Casteletti, Luiz Carlos

    2005-09-15

    Duplex and super duplex stainless steels are ferrous alloys with up to 26% chromium, 8% nickel, 5% molybdenum and 0.3% nitrogen, which are largely used in applications in media containing ions from the halogen family, mainly the chloride ion (Cl{sup -}). The emergence of this material aimed at substituting Copper-Nickel alloys (Cupro-Nickel) that despite presenting good corrosion resistance, has mechanical properties quite inferior to steel properties. The metallurgy of duplex and super duplex stainless steel is complex due to high sensitiveness to sigma phase precipitation that becomes apparent, due to the temperatures they are exposed on cooling from solidification as well as from heat treatment processes. The objective of this study was to verify the influence of heat treating temperatures on the microstructure and hardness of ASTM A890/A890M Gr 6A super duplex stainless steel type. Microstructure control is of extreme importance for castings, as the chemical composition and cooling during solidification inevitably provide conditions for precipitation of sigma phase. Higher hardness in these materials is directly associated to high sigma phase concentration in the microstructure, precipitated in the ferrite/austenite interface. While heat treatment temperature during solution treatment increases, the sigma phase content in the microstructure decreases and consequently, the material hardness diminishes. When the sigma phase was completely dissolved by the heat treatment, the material hardness was influenced only due to ferrite and austenite contents in the microstructure.

  8. Nitrogen containing shielding gases for GTAW duplex stainless steels

    SciTech Connect

    Creffield, G.K.; Cole, M.H.; Paciej, R.; Huang, W.; Urmston, S.

    1993-12-31

    The duplex stainless steel are alloys characterized as consisting of two phases; austenite and ferrite. As such, they combine the benefits of both phases i.e. good ductility and general corrosion resistance of austenite, but with improved stress corrosion cracking resistance and strength associate with ferrite. Carefully controlled manufacturing techniques are employed to produce this combination in roughly equal proportions to ensure optimum properties. The range of duplex alloys studied in this work covered both the standard grade (2205) and the latest generation of super duplex (2507) alloys; typical compositions are shown in Table 1. Although the standard duplex is the most commonly available and widely used, super duplexes, which are characterized by higher chromium, nickel, molybdenum and nitrogen contents, have even better corrosion properties and are finding increasing applications in the offshore industry. To benefit from the superior properties of duplex, it is vital that these alloys can be welded effectively and that the properties of the welded joint match those of the parent weld. The objective of the current investigation was to study the effect of nitrogen, in both the shielding and purge gas, on the weld metal nitrogen content, microstructure and corrosion resistance, with the eventual aim of recommending an effective shielding gas mixture for duplex stainless steels.

  9. Corrosion induced by cathodic hydrogen in 2205 duplex stainless steel

    NASA Astrophysics Data System (ADS)

    Michalska, J.

    2011-05-01

    In this work new results about the influence of cathodic hydrogen on passivity and corrosion resistance of 2205 duplex stainless steel are described. The results were discussed by taking into account hydrogen charged samples and without hydrogen. The corrosion resistance to pitting was qualified with the polarization curves. The conclusion is that, hydrogen deteriorated the passive film stability and corrosion resistance to pitting of 2205 duplex stainless steel. The presence of hydrogen in passive films increases corrosion current density and decreases the potential of the film breakdown. It was also found that degree of susceptibility to hydrogen action was dependent on the hydrogen charging conditions.

  10. Cavitation Erosion of Sensitized UNS S31803 Duplex Stainless Steels

    NASA Astrophysics Data System (ADS)

    Mitelea, Ion; Micu, Lavinia Mădălina; Bordeaşu, Ilare; Crăciunescu, Corneliu Marius

    2016-05-01

    During processing or use, duplex steels can be subjected to heating at high temperatures that can affect their behavior. This work aims to correlate the influence of the sensitization treatment on the ultrasonic cavitation erosion behavior of a UNS S31803 (X2CrNiMoN22-5-3) duplex stainless steel. Duplex stainless steels, formed as a result of rapid cooling after solution annealing, are sensitized at temperatures of 475 and 850 °C, respectively, leading to hardening and embrittlement due to the spinodal decomposition of the ferrite and the precipitation of secondary phases. The ultrasonic cavitation erosion experiments showed that the sensitization at 850 °C reduced the mean depth of erosion by about 11% and the mean depth of erosion rate by 28%. By contrast, the sensitization at 475 °C deteriorates the cavitation erosion resistance, increasing the erosion parameters by up to 22%, compared to the solution annealed state.

  11. Irradiation response of delta ferrite in as-cast and thermally aged cast stainless steel

    SciTech Connect

    Li, Zhangbo; Lo, Wei-Yang; Chen, Yiren; Pakarinen, Janne; Wu, Yaqiao; Allen, Todd; Yang, Yong

    2015-08-08

    To enable the life extension of Light Water Reactors (LWRs) beyond 60 years, it is critical to gain adequate knowledge for making conclusive predictions to assure the integrity of duplex stainless steel reactor components, e.g. primary pressure boundary and reactor vessel internal. Microstructural changes in the ferrite of thermally aged, neutron irradiated only, and neutron irradiated after being thermally aged cast austenitic stainless steels (CASS) were investigated using atom probe tomography. The thermal aging was performed at 400 °C for 10,000 h and the irradiation was conducted in the Halden reactor at ~315 °C to 0.08 dpa (5.6 × 1019 n/cm2 E > 1 MeV). Low dose neutron irradiation at a dose rate of 5 × 10-9 dpa/s was found to induce spinod,al decomposition in the ferrite of as-cast microstructure, and further to enhance the spinodal decomposition in the thermally aged cast alloys. Regarding the G-phase precipitates, the neutron irradiation dramatically increases the precipitate size, and alters the composition of the precipitates with increased, Mn, Ni, Si and Mo and reduced Fe and Cr contents. Lastly, The results have shown that low dose neutron irradiation can further accelerate the degradation of ferrite in a duplex stainless steel at the LWR relevant condition.

  12. Irradiation response of delta ferrite in as-cast and thermally aged cast stainless steel

    DOE PAGES

    Li, Zhangbo; Lo, Wei-Yang; Chen, Yiren; Pakarinen, Janne; Wu, Yaqiao; Allen, Todd; Yang, Yong

    2015-08-08

    To enable the life extension of Light Water Reactors (LWRs) beyond 60 years, it is critical to gain adequate knowledge for making conclusive predictions to assure the integrity of duplex stainless steel reactor components, e.g. primary pressure boundary and reactor vessel internal. Microstructural changes in the ferrite of thermally aged, neutron irradiated only, and neutron irradiated after being thermally aged cast austenitic stainless steels (CASS) were investigated using atom probe tomography. The thermal aging was performed at 400 °C for 10,000 h and the irradiation was conducted in the Halden reactor at ~315 °C to 0.08 dpa (5.6 × 1019more » n/cm2 E > 1 MeV). Low dose neutron irradiation at a dose rate of 5 × 10-9 dpa/s was found to induce spinod,al decomposition in the ferrite of as-cast microstructure, and further to enhance the spinodal decomposition in the thermally aged cast alloys. Regarding the G-phase precipitates, the neutron irradiation dramatically increases the precipitate size, and alters the composition of the precipitates with increased, Mn, Ni, Si and Mo and reduced Fe and Cr contents. Lastly, The results have shown that low dose neutron irradiation can further accelerate the degradation of ferrite in a duplex stainless steel at the LWR relevant condition.« less

  13. Effect of ultrafine grain on tensile behaviour and corrosion resistance of the duplex stainless steel.

    PubMed

    Jinlong, Lv; Tongxiang, Liang; Chen, Wang; Limin, Dong

    2016-05-01

    The ultrafine grained 2205 duplex stainless steel was obtained by cold rolling and annealing. The tensile properties were investigated at room temperature. Comparing with coarse grained stainless steel, ultrafine grained sample showed higher strength and plasticity. In addition, grain size changed deformation orientation. The strain induced α'-martensite was observed in coarse grained 2205 duplex stainless steel with large strain. However, the grain refinement inhibited the transformation of α'-martensite;nevertheless, more deformation twins improved the strength and plasticity of ultrafine grained 2205 duplex stainless steel. In addition, the grain refinement improved corrosion resistance of the 2205 duplex stainless steel in sodium chloride solution. PMID:26952459

  14. Effect of ultrafine grain on tensile behaviour and corrosion resistance of the duplex stainless steel.

    PubMed

    Jinlong, Lv; Tongxiang, Liang; Chen, Wang; Limin, Dong

    2016-05-01

    The ultrafine grained 2205 duplex stainless steel was obtained by cold rolling and annealing. The tensile properties were investigated at room temperature. Comparing with coarse grained stainless steel, ultrafine grained sample showed higher strength and plasticity. In addition, grain size changed deformation orientation. The strain induced α'-martensite was observed in coarse grained 2205 duplex stainless steel with large strain. However, the grain refinement inhibited the transformation of α'-martensite;nevertheless, more deformation twins improved the strength and plasticity of ultrafine grained 2205 duplex stainless steel. In addition, the grain refinement improved corrosion resistance of the 2205 duplex stainless steel in sodium chloride solution.

  15. Duplex stainless steels for the pulp and paper industry

    SciTech Connect

    Alfonsson, E.; Olsson, J.

    1999-07-01

    The metallurgy and corrosion resistance of duplex stainless steel, particularly with regards to applications in the pulp and paper industry, are described. Practical experiences from pressure vessel installations in cooking plants and bleach plants as well as from non-pressurized items in different parts along the fiber line, are given. The paper also reviews corrosion test results presented previously and compares these with recent test data and the practical experiences. Though most of the installations have been successful, some cases of corrosion attacks on duplex stainless steel have been reported, although these are very limited in number: one digester, one calorifier, two pulp storage towers, and two bleach plant filter washers, of a total of more than 700 identified installations.

  16. Magnetic characterisation of duplex stainless steel

    NASA Astrophysics Data System (ADS)

    Mészáros, I.

    2006-02-01

    Heat treatment-induced microstructural processes were studied by different non-destructive magnetic and mechanical material testing methods in the present work. A commercial SAF 2507 type superduplex stainless steel was investigated. This alloy contains about 40% metastable ferrite which can decompose to a sigma phase and secondary austenite due to heat treatment. All the mechanical, corrosion resistance and magnetic properties are strongly influenced by this microstructural changes. This study had two aims: to understand better the kinetics of the ferrite decomposition process and to study the application possibilities of the applied magnetic measurements. This paper presents an application possibility of the nonlinear harmonics analysis measurement and demonstrates the possibility to find a quantitative correlation between measured harmonics and mechanical properties obtained from destructive tests.

  17. Ultrasonic Attenuation Measurements in Thermally Degraded 2205 Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Ruiz, A.; Ortiz, N.; Carreón, H.; Sánchez, A.

    2009-03-01

    Ultrasonic attenuation plays an important role in materials characterization of metal components. This paper present data and discuss ultrasonic attenuation variations in a 2205 duplex stainless steel aged isothermally at 700° C and 900° C for different time intervals. Attenuation measurements as function of frequency where performed using pulse-echo immersion method and broad band planar transducers. Evidence is found of changes in the attenuation coefficient as aging time increases. The corresponding microstructure of aged specimens was observed and impact toughness was measured. Comparison is made with measurements of ferrite content for the two temperatures and different aging times.

  18. Cast Stainless Steel Ferrite and Grain Structure

    SciTech Connect

    Ruud, Clayton O.; Ramuhalli, Pradeep; Meyer, Ryan M.; Mathews, Royce; Diaz, Aaron A.; Anderson, Michael T.

    2012-09-01

    In-service inspection requirements dictate that piping welds in the primary pressure boundary of light-water reactors be subject to a volumetric examination based on the rules contained within the American Society of Mechanical Engineers Boiler and Pressure Vessel Code, Section XI. The purpose of the inspection is the reliable detection and accurate sizing of service-induced degradation and/or material flaws introduced during fabrication. The volumetric inspection is usually carried out using ultrasonic testing (UT) methods. However, the varied metallurgical macrostructures and microstructures of cast austenitic stainless steel piping and fittings, including statically cast stainless steel and centrifugally cast stainless steel (CCSS), introduce significant variations in the propagation and attenuation of ultrasonic energy. These variations complicate interpretation of the UT responses and may compromise the reliability of UT inspection. A review of the literature indicated that a correlation may exist between the microstructure and the delta ferrite content of the casting alloy. This paper discusses the results of a recent study where the goal was to determine if a correlation existed between measured and/or calculated ferrite content and grain structure in CCSS pipe.

  19. Aging degradation of cast stainless steel: status and program

    SciTech Connect

    Chopra, O.K.; Ayrault, G.

    1983-10-01

    A program has been initiated to investigate the significance of in-service embrittlement of cast duplex stainless steels under light-water reactor operating conditions. The existing data are reviewed to determine the critical parameters that control the aging behavior and to define the objectives and scope of the investigation. The test matrices for microstructural studies and mechanical property measurements are presented. The initial experimental effort is focussed on characterizing the microstructure of long-term, low-temperature aged material. Specimens from three heats of cast CF-8 and CF-8M stainless steel aged for up to 70,000 h at 300, 350, and 400/sup 0/C were obtained from George Fisher Ltd., of Switzerland. Initial analyses reveal the formation of three different types of precipitates which are not ..cap alpha..'. An FCC phase, similar to the M/sub 23/C/sub 6/ precipitates, was present in all the long-term aged material. 15 references, 10 figures, 2 tables.

  20. Thermal treatment effects on laser surface remelting duplex stainless steel

    NASA Astrophysics Data System (ADS)

    do Nascimento, Alex M.; Ierardi, Maria Clara F.; Aparecida Pinto, M.; Tavares, Sérgio S. M.

    2008-10-01

    In this paper the microstructural changes and effects on corrosion resistance of duplex stainless steels UNS S32304 and UNS S32205, commonly used by the petroleum industry, were studied, following the execution of laser surface remelting (LSM) and post-thermal treatments (TT). In this way, data was obtained, which could then be compared with the starting condition of the alloys. In order to analyze the corrosion behaviour of the alloys in the as-received conditions, treated with laser and after post-thermal treatments, cyclic polarization tests were carried out. A solution of 3.5% NaCl (artificial sea water) was used, as duplex stainless steels are regularly used by the petroleum industry in offshore locations. The results obtained showed that when laser surface treated, due to rapid resolidification, the alloys became almost ferritic, and since the level of nitrogen in the composition of both alloys is superior to their solubility limit in ferrite, a precipitation of Cr2N (chromium nitrides) occurred in the ferritic matrix, causing loss of corrosion resistance, thus resulting in an increase in surface hardness. However, after the post-thermal treatment the alloys corrosion resistance was restored to values close to those of the as-received condition.

  1. Phase Transformation in Cast Superaustenitic Stainless Steels

    SciTech Connect

    Lee Phillips, Nathaniel Steven

    2006-01-01

    Superaustenitic stainless steels constitute a group of Fe-based alloys that are compositionally balanced to have a purely austenitic matrix and exhibit favorable pitting and crevice corrosion resistant properties and mechanical strength. However, intermetallic precipitates such as sigma and Laves can form during casting or exposure to high-temperature processing, which degrade the corrosion and mechanical properties of the material. The goal of this study was to accurately characterize the solid-solid phase transformations seen in cast superaustenitic stainless steels. Heat treatments were performed to understand the time and temperature ranges for intermetallic phase formations in alloys CN3MN and CK3MCuN. Microstructures were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy and wavelength dispersive spectroscopy (EDS, WDS). The equilibrium microstructures, composed primarily of sigma and Laves within purely austenitic matrices, showed slow transformation kinetics. Factors that determine the extent of transformation, including diffusion, nucleation, and growth, are discussed.

  2. Stress corrosion cracking of duplex stainless steels in caustic solutions

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Ananya

    Duplex stainless steels (DSS) with roughly equal amount of austenite and ferrite phases are being used in industries such as petrochemical, nuclear, pulp and paper mills, de-salination plants, marine environments, and others. However, many DSS grades have been reported to undergo corrosion and stress corrosion cracking in some aggressive environments such as chlorides and sulfide-containing caustic solutions. Although stress corrosion cracking of duplex stainless steels in chloride solution has been investigated and well documented in the literature but the SCC mechanisms for DSS in caustic solutions were not known. Microstructural changes during fabrication processes affect the overall SCC susceptibility of these steels in caustic solutions. Other environmental factors, like pH of the solution, temperature, and resulting electrochemical potential also influence the SCC susceptibility of duplex stainless steels. In this study, the role of material and environmental parameters on corrosion and stress corrosion cracking of duplex stainless steels in caustic solutions were investigated. Changes in the DSS microstructure by different annealing and aging treatments were characterized in terms of changes in the ratio of austenite and ferrite phases, phase morphology and intermetallic precipitation using optical micrography, SEM, EDS, XRD, nano-indentation and microhardness methods. These samples were then tested for general and localized corrosion susceptibility and SCC to understand the underlying mechanisms of crack initiation and propagation in DSS in the above-mentioned environments. Results showed that the austenite phase in the DSS is more susceptible to crack initiation and propagation in caustic solutions, which is different from that in the low pH chloride environment where the ferrite phase is the more susceptible phase. This study also showed that microstructural changes in duplex stainless steels due to different heat treatments could affect their SCC

  3. Casting Stainless-Steel Models Around Pressure Tubes

    NASA Technical Reports Server (NTRS)

    Vasquez, Peter; Micol, John R.

    1992-01-01

    Survivability of thin-wall stainless-steel tubing increased to nearly 100 percent. Improves state of art in pressure-model castings and reduces cost associated with machining complete model from stainless-steel blank.

  4. Hydrogen effects in duplex stainless steel welded joints - electrochemical studies

    NASA Astrophysics Data System (ADS)

    Michalska, J.; Łabanowski, J.; Ćwiek, J.

    2012-05-01

    In this work results on the influence of hydrogen on passivity and corrosion resistance of 2205 duplex stainless steel (DSS) welded joints are described. The results were discussed by taking into account three different areas on the welded joint: weld metal (WM), heat-affected zone (HAZ) and parent metal. The corrosion resistance was qualified with the polarization curves registered in a synthetic sea water. The conclusion is that, hydrogen may seriously deteriorate the passive film stability and corrosion resistance to pitting of 2205 DSS welded joints. The presence of hydrogen in passive films increases corrosion current density and decreases the potential of the film breakdown. It was also found that degree of susceptibility to hydrogen degradation was dependent on the hydrogen charging conditions. WM region has been revealed as the most sensitive to hydrogen action.

  5. Electromagnetic non-destructive technique for duplex stainless steel characterization

    NASA Astrophysics Data System (ADS)

    Rocha, João Vicente; Camerini, Cesar; Pereira, Gabriela

    2016-02-01

    Duplex stainless steel (DSS) is a two-phase (ferrite and austenite) material, which exhibits an attractive combination of mechanical properties and high corrosion resistance, being commonly employed for equipment of petrochemical plants, refining units and oil & gas platforms. The best properties of DSS are achieved when the phases are in equal proportions. However, exposition to high temperatures (e.g. welding process) may entail undesired consequences, such as deleterious phases precipitation (e.g. sigma, chi) and different proportion of the original phases, impairing dramatically the mechanical and corrosion properties of the material. A detailed study of the magnetic behavior of DSS microstructure with different ferrite austenite ratios and deleterious phases content was accomplished. The non destructive method evaluates the electromagnetic properties changes in the material and is capable to identify the presence of deleterious phases into DSS microstructure.

  6. Role of surface finishing on pitting corrosion of a duplex stainless steel in seawater

    NASA Astrophysics Data System (ADS)

    Salah-Rousset, N. Ben; Chaouachi, M. A.; Chellouf, A.

    1996-04-01

    Localized corrosion of duplex UNS S32550 stainless steel in seawater was investigated in the laboratory and in field trials for several surface finish conditions: polished, ground, and sandblasted. Electrochemical data obtained by polarization curves showed that the smoother, polished surface had better characteristics (higher pitting and protection potentials) than the ground or sandblasted surfaces. However, despite its high degree of roughness, the sandblasted surface was the most resistant in field conditions, exhibiting the lowest number of sites attacked. Internal compressive stresses created by sandblasting seem also to have an “unsensitizing” effect on sensitized zones that exist in cast steel (due to repairs of mold defects), reducing its susceptibility to microbiologically influenced corrosion (MIC). Such stresses are not generated in polished or ground surfaces, and localized MIC attack can occur.

  7. Superplastic Forming of Duplex Stainless Steel for Aerospace Part

    SciTech Connect

    Lee, Ho-Sung; Yoon, Jong-Hoon; Yoo, Joon-Tae; Yi, Young-Moo

    2011-08-22

    In this study, the high temperature forming behavior of duplex stainless steel has been characterized and the outer shell of a combustion chamber was fabricated with pressure difference of hot gas. It consists of two parts which are the outer skin made of stainless steel to sustain the internal pressure and the inner shell made of copper alloy for regenerative cooling channels. Two outer skins partitioned to half with respect to the symmetric axis was prepared by hot gas forming process with a maximum pressure of 7 MPa following to FEM analysis. For inner layer, copper alloy was machined for cooling channels and then placed in the gas pressure welding fixture. It is shown that the optimum condition of gas pressure welding is 7 MPa at 890 deg. C, for one hour. EDX analysis and scanning electron microscope micrograph confirm the atomic diffusion process is observed at the interface and copper atoms diffuse into steel, while iron and chrome atoms diffuse into copper. The result shows that the manufacturing method with superplastic forming and gas pressure welding of steel and copper alloy has been successful for near net shape manufacturing of scaled combustion chamber of launch vehicle.

  8. Superplastic Forming of Duplex Stainless Steel for Aerospace Part

    NASA Astrophysics Data System (ADS)

    Lee, Ho-Sung; Yoon, Jong-Hoon; Yoo, Joon-Tae; Yi, Young-Moo

    2011-08-01

    In this study, the high temperature forming behavior of duplex stainless steel has been characterized and the outer shell of a combustion chamber was fabricated with pressure difference of hot gas. It consists of two parts which are the outer skin made of stainless steel to sustain the internal pressure and the inner shell made of copper alloy for regenerative cooling channels. Two outer skins partitioned to half with respect to the symmetric axis was prepared by hot gas forming process with a maximum pressure of 7 MPa following to FEM analysis. For inner layer, copper alloy was machined for cooling channels and then placed in the gas pressure welding fixture. It is shown that the optimum condition of gas pressure welding is 7 MPa at 890 °C, for one hour. EDX analysis and scanning electron microscope micrograph confirm the atomic diffusion process is observed at the interface and copper atoms diffuse into steel, while iron and chrome atoms diffuse into copper. The result shows that the manufacturing method with superplastic forming and gas pressure welding of steel and copper alloy has been successful for near net shape manufacturing of scaled combustion chamber of launch vehicle.

  9. Tensile-property characterization of thermally aged cast stainless steels

    SciTech Connect

    Michaud, W.F.; Toben, P.T.; Soppet, W.K.; Chopra, O.K.

    1994-02-01

    The effect of thermal aging on tensile properties of cast stainless steels during service in light water reactors has been evaluated. Tensile data for several experimental and commercial heats of cast stainless steels are presented. Thermal aging increases the tensile strength of these steels. The high-C Mo-bearing CF-8M steels are more susceptible to thermal aging than the Mo-free CF-3 or CF-8 steels. A procedure and correlations are presented for predicting the change in tensile flow and yield stresses and engineering stress-vs.-strain curve of cast stainless steel as a function of time and temperature of service. The tensile properties of aged cast stainless steel are estimated from known material information, i.e., chemical composition and the initial tensile strength of the steel. The correlations described in this report may be used for assessing thermal embrittlement of cast stainless steel components.

  10. Phase Separation in Lean Grade Duplex Stainless Steel 2101

    SciTech Connect

    Garfinkel, D.; Poplawsky, Jonathan D.; Guo, Wei; Young, Jr., George A.; Tucker, Julie

    2015-08-19

    The use of duplex stainless steels (DSS) in nuclear power generation systems is limited by thermal instability that leads to embrittlement in the temperature range of 204°C - 538°C. New lean grade alloys, such as 2101, offer the potential to mitigate these effects. Thermal embrittlement was quantified through impact toughness and hardness testing on samples of alloy 2101 after aging at 427°C for various durations (1-10,000 hours). Additionally, atom probe tomography (APT) was utilized in order to observe the kinetics of α-α’ separation and G-phase formation. Mechanical testing and APT data for two other DSS alloys, 2003 and 2205 were used as a reference to 2101. The results show that alloy 2101 exhibits superior performance compared to the standard grade DSS alloy, 2205, but inferior to the lean grade alloy, 2003, in mechanical testing. APT data demonstrates that the degree of α-α’ separation found in alloy 2101 closely resembles that of 2205, and greatly exceeds 2003. Additionally, contrary to what was observed in 2003, 2101 demonstrated G-phase like precipitates after long aging times, though precipitates were not as abundant as was observed in 2205.

  11. Eddy current techniques for super duplex stainless steel characterization

    NASA Astrophysics Data System (ADS)

    Camerini, C.; Sacramento, R.; Areiza, M. C.; Rocha, A.; Santos, R.; Rebello, J. M.; Pereira, G.

    2015-08-01

    Super duplex stainless steel (SDSS) is a two-phase material where the microstructure consists of grains of ferrite (δ) and austenite (γ). SDSS exhibit an attractive combination of properties, such as: strength, toughness and stress corrosion cracking resistance. Nevertheless, SDSS attain these properties after a controlled solution heat treatment, leading to a similar volumetric fraction of δ and γ. Any further heat treatment, welding operation for example, can change the balance of the original phases, or may also lead to precipitation of a deleterious phase, such as sigma (σ). For these situations, the material corrosion resistance is severely impaired. In the present study, several SDSS samples with low σ phase content and non-balanced microstructure were intentionally obtained by thermally treating SDSS specimens. Electromagnetic techniques, conventional Eddy Current Testing (ECT) and Saturated Low Frequency Eddy Current (SLOFEC), were employed to characterize the SDSS samples. The results showed that ECT and SLOFEC are reliable techniques to evaluate σ phase presence in SDSS and can provide an estimation of the δ content.

  12. Phase Separation in Lean-Grade Duplex Stainless Steel 2101

    NASA Astrophysics Data System (ADS)

    Garfinkel, David A.; Poplawsky, Jonathan D.; Guo, Wei; Young, George A.; Tucker, Julie D.

    2015-08-01

    The use of duplex stainless steels (DSS) in nuclear power generation systems is limited by thermal instability that leads to embrittlement in the temperature range of 204°C to 538°C. New lean-grade alloys, such as 2101, offer the potential to mitigate these effects. Thermal embrittlement was quantified through impact toughness and hardness testing on samples of alloy 2101 after aging at 427°C for various durations (1-10,000 h). Additionally, atom probe tomography (APT) was utilized in order to observe the kinetics of α-α' separation and G-phase formation. Mechanical testing and APT data for two other DSS alloys, 2003 and 2205, were used as a reference to 2101. The results show that alloy 2101 exhibits superior performance compared to the standard-grade DSS alloy 2205 but inferior to the lean-grade alloy 2003 in mechanical testing. APT data demonstrate that the degree of α-α' separation found in alloy 2101 closely resembles that of 2205 and greatly exceeds 2003. Additionally, contrary to what was observed in 2003, 2101 demonstrated G-phase like precipitates after long aging times, although precipitates were not as abundant as was observed in 2205.

  13. Phase Separation in Lean Grade Duplex Stainless Steel 2101

    DOE PAGES

    Garfinkel, D.; Poplawsky, Jonathan D.; Guo, Wei; Young, Jr., George A.; Tucker, Julie

    2015-08-19

    The use of duplex stainless steels (DSS) in nuclear power generation systems is limited by thermal instability that leads to embrittlement in the temperature range of 204°C - 538°C. New lean grade alloys, such as 2101, offer the potential to mitigate these effects. Thermal embrittlement was quantified through impact toughness and hardness testing on samples of alloy 2101 after aging at 427°C for various durations (1-10,000 hours). Additionally, atom probe tomography (APT) was utilized in order to observe the kinetics of α-α’ separation and G-phase formation. Mechanical testing and APT data for two other DSS alloys, 2003 and 2205 weremore » used as a reference to 2101. The results show that alloy 2101 exhibits superior performance compared to the standard grade DSS alloy, 2205, but inferior to the lean grade alloy, 2003, in mechanical testing. APT data demonstrates that the degree of α-α’ separation found in alloy 2101 closely resembles that of 2205, and greatly exceeds 2003. Additionally, contrary to what was observed in 2003, 2101 demonstrated G-phase like precipitates after long aging times, though precipitates were not as abundant as was observed in 2205.« less

  14. X-mas trees: A new application for duplex stainless steels

    SciTech Connect

    Hochoertler, G.; Zeiler, G.; Haberfellner, K.

    1995-12-31

    The development of fields in severe areas (subsea installations, deserts) necessitates the use of materials which can operate maintenance free in these conditions. Depending on production route and aggressivity of relevant media, the materials used until now, such as AISI 4130, are being superseded by higher alloyed materials such as F6NM, Duplex and Super Duplex Steels. Extensive investigation of metallurgical, mechanical, technological and stress aspects as well as research into the influence of melting, forging and heat treatment processes on high alloyed materials enables ``High Tech`` forgings to be manufactured. Based on investigations and experience gained by previously produced forgings (WYE-piece, Gate Valve components, Swivel forgings, line pipes made of Super Duplex Stainless Steels and Duplex Stainless Steels), the first X-mas trees made of solid Duplex Stainless Steel has been produced. Due to the excellent mechanical and corrosion properties of Duplex Stainless Steel, the expensive and time consuming cladding can be eliminated for most environments, which results in good economy and significantly reduced production time. To obtain information about the quality of such a large forging, samples were taken from one of these X-mas trees and the mechanical and corrosion properties were investigated.

  15. Characterization of microstructure and texture across dissimilar super duplex/austenitic stainless steel weldment joint by super duplex filler metal

    SciTech Connect

    Eghlimi, Abbas; Shamanian, Morteza; Eskandarian, Masoomeh; Zabolian, Azam; Szpunar, Jerzy A.

    2015-08-15

    In the present paper, microstructural changes across an as-welded dissimilar austenitic/duplex stainless steel couple welded by a super duplex stainless steel filler metal using gas tungsten arc welding process is characterized with optical microscopy and electron back-scattered diffraction techniques. Accordingly, variations of microstructure, texture, and grain boundary character distribution of base metals, heat affected zones, and weld metal were investigated. The results showed that the weld metal, which was composed of Widmanstätten austenite side-plates and allotriomorphic grain boundary austenite morphologies, had the weakest texture and was dominated by low angle boundaries. The welding process increased the ferrite content but decreased the texture intensity at the heat affected zone of the super duplex stainless steel base metal. In addition, through partial ferritization, it changed the morphology of elongated grains of the rolled microstructure to twinned partially transformed austenite plateaus scattered between ferrite textured colonies. However, the texture of the austenitic stainless steel heat affected zone was strengthened via encouraging recrystallization and formation of annealing twins. At both interfaces, an increase in the special character coincident site lattice boundaries of the primary phase as well as a strong texture with <100> orientation, mainly of Goss component, was observed. - Graphical abstract: Display Omitted - Highlights: • Weld metal showed local orientation at microscale but random texture at macroscale. • Intensification of <100> orientated grains was observed adjacent to the fusion lines. • The austenite texture was weaker than that of the ferrite in all duplex regions. • Welding caused twinned partially transformed austenites to form at SDSS HAZ. • At both interfaces, the ratio of special CSL boundaries of the primary phase increased.

  16. Development of nano-structured duplex and ferritic stainless steels by pulverisette planetary milling followed by pressureless sintering

    SciTech Connect

    R, Shashanka Chaira, D.

    2015-01-15

    Nano-structured duplex and ferritic stainless steel powders are prepared by planetary milling of elemental Fe, Cr and Ni powder for 40 h and then consolidated by conventional pressureless sintering. The progress of milling and the continuous refinement of stainless steel powders have been confirmed by means of X-ray diffraction and scanning electron microscopy. Activation energy for the formation of duplex and ferritic stainless steels is calculated by Kissinger method using differential scanning calorimetry and is found to be 159.24 and 90.17 KJ/mol respectively. Both duplex and ferritic stainless steel powders are consolidated at 1000, 1200 and 1400 °C in argon atmosphere to study microstructure, density and hardness. Maximum sintered density of 90% and Vickers microhardness of 550 HV are achieved for duplex stainless steel sintered at 1400 °C for 1 h. Similarly, 92% sintered density and 263 HV microhardness are achieved for ferritic stainless steel sintered at 1400 °C. - Highlights: • Synthesized duplex and ferritic stainless steels by pulverisette planetary milling • Calculated activation energy for the formation of duplex and ferritic stainless steels • Studied the effect of sintering temperature on density, hardness and microstructure • Duplex stainless steel exhibits 90% sintered density and microhardness of 550 HV. • Ferritic stainless steel shows 92% sintered density and 263 HV microhardness.

  17. Procedure for flaw detection in cast stainless steel

    DOEpatents

    Kupperman, David S.

    1988-01-01

    A method of ultrasonic flaw detection in cast stainless steel components incorporating the steps of determining the nature of the microstructure of the cast stainless steel at the site of the flaw detection measurements by ultrasonic elements independent of the component thickness at the site; choosing from a plurality of flaw detection techniques, one such technique appropriate to the nature of the microstructure as determined and detecting flaws by use of the chosen technique.

  18. The effects of laser welding parameters on the microstructure of ferritic and duplex stainless steels welds

    NASA Astrophysics Data System (ADS)

    Pekkarinen, J.; Kujanpää, V.

    This study is focused to determine empirically, which microstructural changes occur in ferritic and duplex stainless steels when heat input is controlled by welding parameters. Test welds were done autogenously bead-on-plate without shielding gas using 5 kW fiber laser. For comparison, some gas tungsten arc welds were made. Used test material were 1.4016 (AISI 430) and 1.4003 (low-carbon ferritic) type steels in ferritic steels group and 1.4162 (low-alloyed duplex, LDX2101) and 1.4462 (AISI 2205) type steels in duplex steels group. Microstructural changes in welds were identified and examined using optical metallographic methods.

  19. Effect of aging on impact properties of ASTM A890 Grade 1C super duplex stainless steel

    SciTech Connect

    Martins, Marcelo Forti, Leonardo Rodrigues Nogueira

    2008-02-15

    Super duplex stainless steels in the solution annealed condition are thermodynamically metastable systems which, when exposed to heat, present a strong tendency to 'seek' the most favorable thermodynamic condition. The main purpose of this study was to characterize the microstructure of a super duplex stainless steel in the as cast and solution annealed conditions, and to determine the influence of aging heat treatments on its impact strength, based on Charpy impact tests applied to V-notched test specimens. The sigma phase was found to begin precipitating at heat treatment temperatures above 760 deg. C and to dissolve completely only above 1040 deg. C, with the highest peak concentration of this phase appearing at close to 850 deg. C. Heat treatments conducted at temperatures of 580 deg. C to 740 deg. C led to a reduction of the energy absorbed in the Charpy impact test in response to the precipitation of a particulate phase with particle sizes ranging from 0.5 {mu}m to 1.0 {mu}m, with a chromium and iron-rich chemical composition.

  20. The {sigma} phase formation in annealed UNS S31803 duplex stainless steel: Texture aspects

    SciTech Connect

    Souza, C.M. Abreu, H.F.G.; Tavares, S.S.M.; Rebello, J.M.A.

    2008-09-15

    The influence of sigma phase precipitation on the texture of austenite in a duplex stainless steel UNS S31803 was investigated. Sigma phase quantification was precisely performed by electron backscattered scanning diffraction (EBSD) for some conditions. It was found that the increase of the sigma phase precipitation enhances the amount of Brass texture in the austenite phase.

  1. Electrochemical Behavior of 2205 Duplex Stainless Steel in NaCl Solution with Different Chromate Contents

    NASA Astrophysics Data System (ADS)

    Luo, H.; Dong, C. F.; Cheng, X. Q.; Xiao, K.; Li, X. G.

    2012-07-01

    The electrochemical behavior of 2205 duplex stainless steel in NaCl solution with different chromate contents were investigated by potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), Mott-Schottky analysis, and scanning electron microscope (SEM). The effect of chromate on passivity and pitting behavior of stainless steel was also studied. The results showed that pitting susceptibility as well as semiconducting properties of passive film is heavily dependent on the chromate concentration. There exists a critical chromate value (about 0.03 M in 1 M NaCl solutions) below which the pitting corrosion on the stainless steel would be inhibited and above which it would be accelerated.

  2. Laser Shock Processing with Different Conditions of Treatment on Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Castañeda, E.; Rubio-Gonzalez, C.; Chavez-Chavez, A.; Gomez-Rosas, G.

    2015-06-01

    The laser shock processing (LSP) has been developed as an effective alternative to traditional methods for improvement of metallic materials properties and as surface treatment to metals. Duplex stainless steel is a material that has a microstructure formed by two phases, with approximately equal amounts of each one. This stainless steel has wide applications in different fields like shipping, petrochemical, and chemical industries. We present results of the LSP performance using two pulse density configurations of 2500 and 5000 pulses/cm2, both of them at laser irradiation of 532 and 1064 nm (keeping approximately constant power density), in order to treat in under water-jet the surface of 2205 duplex stainless steel samples without coating. A flat mirror and a converging lens is used to deliver 400 mJ/pulse, (5 ns FWHM, 1.1 mm spot diameter with 532 nm wavelength) and 850 mJ/pulse, (6 ns FWHM, 1.5 mm spot diameter with 1064 nm wavelength) laser pulse produced by 10 Hz Q-switched Nd:YAG laser. A motor-controlled x-y precision stage is used, for sweep the treated zone on sample. The use of two wavelengths with approximately the same power density is an effective way for obtaining high compressive residual stresses (~90% of the yield stress). An improvement of hardness (12-25%) at the surface of 2205 duplex stainless steel due to LSP is presented.

  3. Shrinkage Prediction for the Investment Casting of Stainless Steels

    SciTech Connect

    Sabau, Adrian S

    2007-01-01

    In this study, the alloy shrinkage factors were obtained for the investment casting of 17-4PH stainless steel parts. For the investment casting process, unfilled wax and fused silica with a zircon prime coat were used for patterns and shell molds, respectively. Dimensions of the die tooling, wax pattern, and casting were measured using a Coordinate Measurement Machine in order to obtain the actual tooling allowances. The alloy dimensions were obtained from numerical simulation results of solidification, heat transfer, and deformation phenomena. The numerical simulation results for the shrinkage factors were compared with experimental results.

  4. Kinetics and mechanism of thermal aging embrittlement of duplex stainless steels

    SciTech Connect

    Chung, H.M.; Chopra, O.K.

    1987-06-01

    Microstructural characteristics of long-term-aged cast duplex stainless steel specimens from eight laboratory heats and an actual component from a commercial boiling water reactor have been investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), small angle neutron scattering (SANS), and atom probe field ion microscopy (APFIM) techniques. Three precipitate phases, i.e., Cr-rich ..cap alpha..' and the Ni- and Si-rich G phase, and ..gamma../sub 2/ austenite, have been identified in the ferrite matrix of the aged specimens. For CF-8 grade materials, M/sub 23/C/sub 6/ carbides were identified on the austenite-ferrite boundaries as well as in the ferrite matrix for aging at greater than or equal to 450/sup 0/C. It has been shown that Si, C, and Mo contents are important factors that influence the kinetics of the G-phase precipitation. However, TEM and APFIM analyses indicate that the embrittlement for less than or equal to400/sup 0/C aging is primarily associated with Fe and Cr segregation in ferrite by spinodal decomposition. For extended aging, e.g., 6 to 8 years at 350 to 400/sup 0/C, large platelike ..cap alpha..' formed by nucleation and growth from the structure produced by the spinodal decomposition. The Cr content appears to play an important role either to promote the platelike ..cap alpha..' (high Cr content) or to suppress the ..cap alpha..' in favor of ..gamma../sub 2/ precipitation (low Cr). Approximate TTT diagrams for the spinodal, ..cap alpha..', G, ..gamma../sub 2/, and the in-ferrite M/sub 23/C/sub 6/ have been constructed for 250 to 450/sup 0/C aging. Microstructural modifications associated with a 550/sup 0/C reannealing and a subsequent toughness restoration are also discussed. It is shown that the toughness restoration is associated primarily with the dissolution of the Cr-rich region in ferrite.

  5. Characterization of passive film on 2205 duplex stainless steel in sodium thiosulphate solution

    NASA Astrophysics Data System (ADS)

    Luo, H.; Dong, C. F.; Xiao, K.; Li, X. G.

    2011-10-01

    The electrochemical behaviour of passive film formed on 2205 duplex stainless steel in 0.1 M Na 2S 2O 3 solutions was investigated using potentiodynamic polarization, EIS, Mott-Schottky analysis and the compositions of oxide film in different passive regions were carried out by XPS. The results indicated that the impedance is dependent on the applied potential indicating the occurrence of a charge transfer reaction in a porous film. The doping densities evaluated from Mott-Schottky plots demonstrated that there existence of two donor levels in the space charge layer of the passive films. The donor density ( ND1 and ND2 ) values are in the range of 10 20-10 21 cm 3, and decreases exponentially with increasing film formation potential, which is in good agreement with the theoretical consequences of the PDM. The polarization curve and XPS results shows that in the passive regions the 2205 duplex stainless steel exhibits different electrochemical and semiconductor properties.

  6. Corrosion failure of duplex stainless steel equipment in a PVC plant

    SciTech Connect

    Davies, M.; Potgieter, G.

    2000-05-01

    After <9 months of operation in a polyvinyl chloride (PVC) manufacturing plant, alloy 2205 duplex stainless steel (UNS 31803) columns and spiral heat exchangers (HXs) were corroding and cracking. The columns were repaired and remained in service but the HXs needed to be replaced. Candidate materials for the HXs were assessed, and it was found that the super-austenitic alloys containing 6% molybdenum would be more appropriate for this application.

  7. Phase Transformations During the Low-Temperature Nitriding of AISI 2205 Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Yan, Jing; Gu, Tan; Qiu, Shaoyu; Wang, Jun; Xiong, Ji; Fan, Hongyuan

    2015-02-01

    Liquid nitriding of type AISI 2205 duplex stainless steel was conducted at 723 K (450 °C), using one type of novel low-temperature liquid chemical thermo-treatment. The transformation of the nitrided surface microstructure was systematically studied. Experimental results revealed that a nitrided layer formed on the sample surface with the thickness ranging from 3 to 28 μm, depending on nitriding time. After the 2205 duplex stainless steel was subjected to liquid nitriding 723 K (450 °C) for less than 8 hours, the pre-existing ferrite region on the surface transformed into the expanded austenite (S phase) by the infusion of nitrogen atoms, most of which stay in the interstitial sites. Generally, the dominant phase of the nitrided layer was the expanded austenite. When the nitriding time prolonged up to 16 hours, some pre-existing ferrite in expanded austenite was decomposed and ɛ-nitride precipitated subsequently. When the treatment time went up to 40 hours, large amount of ɛ-nitride and CrN precipitates were observed in the pre-existing ferritic region in the expanded austenite. Furthermore, many nitrides precipitated from the pre-austenite region. Acicular nitride was identified by transmission electron microscopy. The thickness of the nitrided layer increased with increasing nitriding time. The growth of the nitrided layer is mainly due to nitrogen diffusion in accordance with the expected parabolic rate law. Liquid nitriding effectively increased the surface hardness of 2205 duplex stainless steel by a factor of 3.

  8. Microstructure/property relationships in dissimilar welds between duplex stainless steels and carbon steels

    SciTech Connect

    Barnhouse, E.J.; Lippold, J.C.

    1998-12-01

    The metallurgical characteristics, toughness and corrosion resistance of dissimilar welds between duplex stainless steel Alloy 2205 and carbon steel A36 have been evaluated. Both duplex stainless steel ER2209 and Ni-based Alloy 625 filler metals were used to join this combination using a multipass, gas tungsten arc welding (GTAW) process. Defect-free welds were made with each filler metal. The toughness of both the 625 and 2209 deposits were acceptable, regardless of heat input. A narrow martensitic region with high hardness was observed along the A36/2209 fusion boundary. A similar region was not observed in welds made with the 625 filler metal. The corrosion resistance of the welds made with 2209 filler metal improved with increasing heat input, probably due to higher levels of austenite and reduced chromium nitride precipitation. Welds made with 625 exhibited severe attack in the root pass, while the bulk of the weld was resistant. This investigation has shown that both filler metals can be used to joint carbon steel to duplex stainless steels, but that special precautions may be necessary in corrosive environments.

  9. Development of Cast Alumina-Forming Austenitic Stainless Steels

    NASA Astrophysics Data System (ADS)

    Muralidharan, G.; Yamamoto, Y.; Brady, M. P.; Walker, L. R.; Meyer, H. M., III; Leonard, D. N.

    2016-09-01

    Cast Fe-Ni-Cr chromia-forming austenitic stainless steels with Ni levels up to 45 wt.% are used at high temperatures in a wide range of industrial applications that demand microstructural stability, corrosion resistance, and creep strength. Although alumina scales offer better corrosion protection at these temperatures, designing cast austenitic alloys that form a stable alumina scale and achieve creep strength comparable to existing cast chromia-forming alloys is challenging. This work outlines the development of cast Fe-Ni-Cr-Al austenitic stainless steels containing about 25 wt.% Ni with good creep strength and the ability to form a protective alumina scale for use at temperatures up to 800-850°C in H2O-, S-, and C-containing environments. Creep properties of the best alloy were comparable to that of HK-type cast chromia-forming alloys along with improved oxidation resistance typical of alumina-forming alloys. Challenges in the design of cast alloys and a potential path to increasing the temperature capability are discussed.

  10. Cast alumina forming austenitic stainless steels

    DOEpatents

    Muralidharan, Govindarajan; Yamamoto, Yukinori; Brady, Michael P

    2013-04-30

    An austenitic stainless steel alloy consisting essentially of, in terms of weight percent ranges 0.15-0.5C; 8-37Ni; 10-25Cr; 2.5-5Al; greater than 0.6, up to 2.5 total of at least one element selected from the group consisting of Nb and Ta; up to 3Mo; up to 3Co; up to 1W; up to 3Cu; up to 15Mn; up to 2Si; up to 0.15B; up to 0.05P; up to 1 total of at least one element selected from the group consisting of Y, La, Ce, Hf, and Zr; <0.3Ti+V; <0.03N; and, balance Fe, where the weight percent Fe is greater than the weight percent Ni, and wherein the alloy forms an external continuous scale comprising alumina, and a stable essentially single phase FCC austenitic matrix microstructure, the austenitic matrix being essentially delta-ferrite free and essentially BCC-phase-free. A method of making austenitic stainless steel alloys is also disclosed.

  11. Study of Aging Effects in 2205 Duplex Stainless Steel Using Thermoelectric Power Measurement

    NASA Astrophysics Data System (ADS)

    Lara, N.; Ruiz, A.; Carreón, H.; Medina, A.; Sánchez, A.

    2010-02-01

    Thermoelectric power (TEP) measurements have been used as an effective method for evaluating the metallurgical state of various alloys. In the steel industry, some fabrication processes promote phase transformation and second phase precipitations which affect the material properties. Assessment of mechanical properties is critical in order to ensure quality of components. This work was conducted in order to evaluate the influence of the aging state of 2205 duplex stainless steel on TEP values. Commercial 2205 duplex steel was isothermally aged at 650 °C 700 °C and 900 °C at different aging times. TEP measurement technique was applied as a non destructive assessment technique to characterize the aging kinetics of the aged 2205 duplex stainless steel, hardness Rockwell (RC) and Charpy impact test were preformed to observe the effect of aging time on the specimens. Metallographic analysis was used to monitor phase transformation and sigma phase precipitation caused by the spinodal decomposition process of ferrite into secondary austenite and sigma phase. Results indicate that that the TEP is sensitive to gradual microstructural changes produced by the aging treatments.

  12. STUDY OF AGING EFFECTS IN 2205 DUPLEX STAINLESS STEEL USING THERMOELECTRIC POWER MEASUREMENT

    SciTech Connect

    Lara, N.; Ruiz, A.; Carreon, H.; Medina, A.; Sanchez, A.

    2010-02-22

    Thermoelectric power (TEP) measurements have been used as an effective method for evaluating the metallurgical state of various alloys. In the steel industry, some fabrication processes promote phase transformation and second phase precipitations which affect the material properties. Assessment of mechanical properties is critical in order to ensure quality of components. This work was conducted in order to evaluate the influence of the aging state of 2205 duplex stainless steel on TEP values. Commercial 2205 duplex steel was isothermally aged at 650 deg. C 700 deg. C and 900 deg. C at different aging times. TEP measurement technique was applied as a non destructive assessment technique to characterize the aging kinetics of the aged 2205 duplex stainless steel, hardness Rockwell (RC) and Charpy impact test were preformed to observe the effect of aging time on the specimens. Metallographic analysis was used to monitor phase transformation and sigma phase precipitation caused by the spinodal decomposition process of ferrite into secondary austenite and sigma phase. Results indicate that that the TEP is sensitive to gradual microstructural changes produced by the aging treatments.

  13. Microstructure and mechanical properties of duplex stainless steel subjected to hydrostatic extrusion

    SciTech Connect

    Maj, P.; Adamczyk-Cieślak, B.; Mizera, J.; Pachla, W.; Kurzydłowski, K.J.

    2014-07-01

    The nanostructure and mechanical properties of ferritic-austenitic duplex stainless steel subjected to hydrostatic extrusion were examined. The refinement of the structure in the initial state and in the two deformation states (ε = 1.4 and ε = 3.8) was observed in an optical microscope (OM) and a transmission electron microscope (TEM). The results indicate that the structure evolved from microcrystalline with a grain size of about 4 μm to nanocrystalline with a grain size of about 150 nm in ferrite and 70 nm in austenite. The material was characterized mechanically by tensile tests performed in the two deformation states. The ultimate strength appeared to increase significantly compared to that in the initial deformation stages, which can be attributed to the grain refinement and plastic deformation. The heterogeneity observed in microregions results from the dual-phase structure of the steel. The results indicate that hydrostatic extrusion is a highly potential technology suitable for improving the properties of duplex steels. - Highlights: • Duplex stainless steel was hydro extruded to a total strain of 3.8 • After the last stage of deformation heterogeneous structure was obtained in the material • As a result of stresses non-diffusive transformation γ→α’ occurred in the material • Nanometric (sub)grains were obtained in the austenite regions.

  14. Evaluation of manual ultrasonic inspection of cast stainless steel piping

    SciTech Connect

    Taylor, T.T.

    1984-05-01

    Two studies have attempted to determine the degree of inspectability of centrifugally cast stainless steel (CCSS) pipe. In one study, Westinghouse examined the reliability of ultrasonic test methods in the detection of mechanical fatigue cracks. The second study was an NRC-sponsored Pipe Inspection Round Robin (PIRR) test conducted at Pacific Northwest Laboratory (PNL). The Westinghouse study reported that 80% detection was achieved for mechanical fatigue cracks having 20% throughwall depth. The PNL study reported that less than 30% detection was achieved for thermal fatigue cracks ranging from 5% to 50% through-wall. A cooperative program between PNL and Westinghouse was conducted to resolve the differences between the two studies. The program was designed as a limited round robin. Detection experiments were performed on samples from both the PNL and Westinghouse studies. The data reported here indicate that flaw type (thermal fatigue versus mechanical fatigue) was a significant factor in detection. Mechanical fatigue cracks were more easily detected than thermal fatigue cracks. The data conclusively show that manual ultrasonic inspection cannot size flaws in cast stainless steel material. The study recommends that ultrasonic inspection of cast stainless steel pipe be continued because cracks caused by some failure mechanisms (i.e., mechanical fatigue cracks) have proven to be detectable.

  15. Internal friction study of decomposition kinetics of SAF 2507 type duplex stainless steel

    SciTech Connect

    Smuk, O.; Smuk, S.; Hanninen, H.; Jagodzinski, Yu.; Tarasenko, O.

    1999-01-08

    During the last decade, super duplex stainless steels (DSSs) with increased nitrogen content have been an object of intensive studies. Present work is devoted to the study of the peculiarities of {delta}-ferrite decomposition in SAF 2507 type duplex steel, and redistribution of nitrogen between ferrite and austenite phases in a wide temperature range by means of internal fraction (IF). Unlike local methods of electron microscopy or engineering methods of hardness or impact toughness testing, which give basically information on the formation of brittle intermetallic phases, the internal friction technique allows to study the state of solid solution and kinetics of changes in the relative amounts of ferrite and austenite phases during thermal treatment.

  16. Distinguishing between chi and sigma phases in duplex stainless steels using potentiostatic etching

    SciTech Connect

    Jackson, E.M.L.E.M.; Visser, P.E. de . Physical Metallurgy Div.); Cornish, L.A. )

    1993-12-01

    A color interference film etching technique based on the principle of potentiostatic etching has been developed to distinguish, by optical metallography, between Cr-rich sigma and Mo-rich chi phases as well as with simultaneous identification of the ferrite and austenite phases in duplex stainless steels. The optical metallography results are confirmed by semiquantitative energy dispersive spectrometry analysis and back-scattered electron imaging. The technique is relatively simple and rapid, and makes use of low voltages and a hot etchant. Results have shown distinctively the sigma, chi, ferrite, and austenite phases, and enable observation of the microstructural development, morphology, and kinetics of formation of the phases in duplex alloys. The method, by giving excellent color contrast between sigma and chi, also facilitates quantitative image analysis of the sigma and chi volume fractions.

  17. Effect of Preaging Deformation on Aging Characteristics of 2507 Super Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Mishra, M. K.; Rao, A. G.; Sarkar, R.; Kashyap, B. P.; Prabhu, N.

    2016-02-01

    In the present study, precipitation of sigma (σ) phase was investigated over the temperature range of 700-850 °C in undeformed and deformed (60% cold rolling) samples of 2507 super duplex stainless steel. The fraction of sigma phase formed as a result of the transformation α → σ + γ2 increases with increasing time and temperature. The increase in sigma phase leads to increase in yield strength and decrease in ductility. Preaging deformation leads to accelerated precipitation of sigma phase. The activation energy for sigma phase precipitation in deformed sample is found to be lower than that in undeformed sample.

  18. EBSD investigation of the microstructure and texture characteristics of hot deformed duplex stainless steel.

    PubMed

    Cizek, P; Wynne, B P; Rainforth, W M

    2006-05-01

    The microstructure and crystallographic texture characteristics were studied in a 22Cr-6Ni-3Mo duplex stainless steel subjected to plastic deformation in torsion at a temperature of 1000 degrees C using a strain rate of 1 s(-1). High-resolution EBSD was successfully used for precise phase and substructural characterization of this steel. The austenite/ferrite ratio and phase morphology as well as the crystallographic texture, subgrain size, misorientation angles and misorientation gradients corresponding to each phase were determined over large sample areas. The deformation mechanisms in each phase and the interrelationship between the two are discussed. PMID:16774517

  19. Process for stabilizing dimensions of duplex stainless steels for service at elevated temperatures

    DOEpatents

    Hull, Frederick C.; Tobin, John C.

    1981-01-01

    Duplex stainless steel materials containing austenite plus delta ferrite, are dimensionally stabilized by heating the material to a reaction temperature between about 1050.degree.-1450.degree. F. (566.degree.-788.degree. C.), holding it at this temperature during transformation of delta ferrite to austenite plus sigma phase, and subsequently heating to a reversion temperature between about 1625.degree.-1750.degree. F. (885.degree.-954.degree. C.), whereby the sigma phase transforms back to ferrite, but the austenite remains dispersed in the ferrite phase. Final controlled cooling permits transformation of ferrite to austenite plus sigma and, later, precipitation of carbides.

  20. Ultrasonic characterization of centrifugally cast stainless steel: Topical report

    SciTech Connect

    Jeong, P.

    1987-06-01

    Ultrasonic wave propagation in centrifugally cast stainless steel (CCSS) was investigated. The difficulties of inspecting CCSS material stem from elastic anisotropy that hampers defect location and severe attenuation caused by coarse grains within the structure that makes defect detection difficult. During this investigation, grain effects on ultrasonic wave propagation were investigated, techniques for identifying different grain structures were developed, and compensation methods for grain effects were addressed. Each step is explained analytically based on relevant theory and proven experimentally. Experiments were conducted on specially designed test specimens: angled blocks, polygonal blocks, wedge blocks, and calibration blocks. Wave parameters such as phase velocity, skew angle, energy velocity, attenuation, beam width, amplitude variation patterns, and frequency dependence on grain structures were all measured with these specimens. CCSS grain structures investigated were equiaxed-fine grains, columnar-dendritic grains, and coarse grains. For comparison purposes, additional types of material such as static-cast stainless steel, forged stainless steel, and carbon steel materials were also investigated. Longitudinal wave, horizontally and vertically polarized shear wave modes were all considered in experiments. The use of an automated ultrasonic system was also demonstrated for grain structure identification.

  1. Yb-fibre Laser Welding of 6 mm Duplex Stainless Steel 2205

    NASA Astrophysics Data System (ADS)

    Bolut, M.; Kong, C. Y.; Blackburn, J.; Cashell, K. A.; Hobson, P. R.

    Duplex stainless steel (DSS) is one of the materials of choice for structural and nuclear applications, having high strength and good corrosion resistance when compared with other grades of stainless steel. The welding process used to join these materials is critical as transformation of the microstructure during welding directly affects the material properties. High power laser welding has recently seen an increase in research interest as it offers both speed and flexibility. This paper presents an investigation into the important parameters affecting laser welding of DSS grade 2205, with particular focus given to the critical issue of phase transformation during welding. Bead-on-plate melt-run trials without filler material were performed on 6mm thick plates using a 5 kW Yb-fibre laser. The laser beam was characterized and a Design of Experiment approach was used to quantify the impact of the process parameters. Optical metallographic methods were used to examine the resulting microstructures.

  2. Application of martensitic, modified martensitic and duplex stainless steel bar stock for completion equipment

    SciTech Connect

    Bhavsar, R.B.; Montani, R.

    1998-12-31

    Martensitic and duplex stainless steel tubing are commonly used for oil and gas applications containing CO{sub 2}. Completion equipment manufacturing requires use of solid round bar or heavy wall hollows. Material properties for this stock are not identical in all cases. Material properties as well as corrosion characteristics are discussed for 13Cr, 13Cr-5Ni-2Mo and 25Cr alloys. Corrosion testing of modified or Enhanced 13Cr solid bar stock, UNS S41425 and other compositions in H{sub 2}S-Cl{sup {minus}} and pH is reported in coupled and uncoupled condition. Corrosion testing of various super duplex bar stock at various H{sub 2}S-chlorides and temperature in CO{sub 2} environment is reported. Impact value requirements, welding issues and special consideration required for these alloys for completion equipment is discussed. Modified 13Cr and Super Duplex Oil Country Tubular Goods (OCTG) are readily available, however, availability of completion equipment raw material compatible with these OCTG is limited.

  3. In-Situ Observations of Phase Transformations in the HAZ of 2205 Duplex Stainless Steel Weldments

    SciTech Connect

    Palmer, T A; Elmer, J W; Wong, J

    2001-08-15

    Ferrite ({delta})/austenite ({gamma}) transformations in the heat affected zone (HAZ) of a gas tungsten arc (GTA) weld in 2205 duplex stainless steel are observed in real-time using spatially resolved X-ray diffraction (SRXRD) with high intensity synchrotron radiation. A map showing the locations of the {delta} and {gamma} phases with respect to the calculated weld pool dimensions has been constructed from a series of SRXRD scans. Regions of liquid, completely transformed {gamma}, a combination of partially transformed {gamma} with untransformed {delta}, and untransformed {delta}+{gamma} are identified. Analysis of each SRXRD pattern provides a semi-quantitative definition of both the {delta}/{gamma} phase balance and the extent of annealing which are mapped for the first time with respect to the calculated weld pool size and shape. A combination of these analyses provides a unique real-time description of the progression of phase transformations in the HAZ. Using these real-time observations, important kinetic information about the transformations occurring in duplex stainless steels during heating and cooling cycles typical of welding can be determined.

  4. Role of structural orientation on the susceptibility of 2205 duplex stainless steel to hydrogen embrittlement

    NASA Astrophysics Data System (ADS)

    Sharrfeddin, A.; Musa, S. M.; Elshawesh, F. M.

    2012-09-01

    Relationship between the microstructure directionality of delta ferrite and austenite islands and the crack morphology, crack velocity and time to failure of the mechanically notched duplex stainless samples tested in hydrogen bearing environment was assessed in aqueous solution of 3.5% seawater. A number of UNS S32205 duplex stainless steel samples were mechanically notched in perpendicular and transverse directions with respect to the austenite and ferrite rolling direction were subjected to slow tensile strain at 21.2 nm/s while undergoing cathodic charging in aqueous solution of 3.5% seawater. In order to assess the role of hydrogen content on embrittlement the hydrogen charging was conducted at various cathodic potentials of -800 mV/SCE to -1300 mV/SCE at two different pH (6.7 and 3.5). Generally, the longitudinal samples showed lower susceptibility to hydrogen embrittlement compared with the transverse samples. The results also confirm that long austenite island can act as an obstacle for propagated crack owing to its low diffusivity and high solubility to the hydrogen.

  5. Precipitation of Chromium Nitrides in the Super Duplex Stainless Steel 2507

    NASA Astrophysics Data System (ADS)

    Pettersson, Niklas; Pettersson, Rachel F. A.; Wessman, Sten

    2015-03-01

    Precipitation of chromium nitrides during cooling from temperatures in the range 1373 K to 1523 K (1100 °C to 1250 °C) has been studied for the super duplex stainless steel 2507 (UNS S32750). Characterization with optical, scanning and transmission electron microscopy was combined to quantify the precipitation process. Primarily Cr2N nitrides were found to precipitate with a high density in the interior of ferrite grains. An increased cooling rate and/or an increased austenite spacing clearly promoted nitride formation, resulting in precipitation within a higher fraction of the ferrite grains, and lager nitride particles. Furthermore, formation of the meta-stable CrN was induced by higher cooling rates. The toughness seemed unaffected by nitrides. A slight decrease in pitting resistance was, however, noticed for quenched samples with large amounts of precipitates. The limited adverse effect on pitting resistance is attributed to the small size (~200 nm) of most nitrides. Slower cooling of duplex stainless steels to allow nitrogen partitioning is suggested in order to avoid large nitrides, and thereby produce a size distribution with a smaller detrimental effect on pitting resistance.

  6. Effect of ageing on precipitation and impact energy of 2101 economical duplex stainless steel

    SciTech Connect

    Zhang Wei; Jiang Laizhu Hu Jincheng; Song Hongmei

    2009-01-15

    The impact energy and microstructure of a thermally aged 2101 duplex stainless steel with composition of Fe-21.4Cr-1.2Ni-5.7Mn-0.23 N-0.31Mo were studied. The results showed that the room temperature impact energy of specimens decreased gradually with ageing temperature up to 700 deg. C and then increased with aging over 700 deg. C. The minimum value of impact energy was 37 J after 700 deg. C aging, which was only 34% of that for as-annealed specimens. For specimens aged at 700 deg. C, the room temperature impact energy decreased significantly after 3 min and was halved after 10 min. Fractographs showed that, with increasing aging time, the fracture morphology changed from fibrous fracture to transgranular and intragranular fracture. Scanning electron micrographs revealed that many precipitates were distributed along {alpha}/{gamma} and {alpha}/{alpha} interfaces. The precipitates were extracted and confirmed by X-ray diffraction to be Cr{sub 2}N. Therefore, it can be concluded that precipitation of Cr{sub 2}N is the main reason for the decrease of impact energy in aged 2101 duplex stainless steel.

  7. Quality control and assurance program for duplex stainless steels, field experience

    SciTech Connect

    Mekhjian, M.; Richard, D.; Nemzer, A.

    1994-12-31

    Duplex stainless steels have proven to be cost effective alternatives to more highly alloyed materials in chloride environments in which conventional 300 series austenitic stainless steels suffer from stress corrosion cracking. However, improper welding of these alloys can cause significant reduction in their corrosion resistance. Close monitoring of welding during fabrication and tight quality control is necessary to ensure that sound weld metal microstructure is obtained with optimum corrosion resistance. One of FMC`s primary applications for duplex stainless steels has been in large scrubbers units in chemical processing plants. In the fabrication of these scrubbers, training of the fabricators and welders was necessary as a part of the total quality control and assurance program. Corrosion testing was performed on coupons removed from each welding procedure qualification test plate and from run-off tabs removed from production welds. The corrosion tests were performed in ferric chloride. Although ferric chloride is not a realistic service environment for these alloys, it has been widely used for screening purposes and successfully indicates the presence of undesirable microstructures. Two deposited weld microstructures were identified as being most susceptible to pitting in the samples examined. These were areas with high ferrite containing precipitates and reheated areas of multiple pass welds with a high secondary austenite content. Field experience showed that relying only on monitoring and controlling the welding heat input, preheat and interpass temperatures, may not be sufficient for ensuring the corrosion resistance of the finished weldment and additional corrosion testing should be done. The materials tested were weldments of alloy 2205 (UNS S31803) and alloy 255 (LTNS S32550).

  8. Studies of aged cast stainless steel from the Shippingport reactor

    SciTech Connect

    Chopra, O.K.

    1990-10-01

    Charpy-impact and tensile tests were conducted on several cast stainless steel materials from the Shippingport reactor. Baseline mechanical properties for unaged material were determined from tests on either recovery-annealed material, i.e., annealed for 1 h at 550{degree}C and water-quenched, or material from the cooler region of the component. The materials indicate relatively modest decreases in impact energy. The results show good agreement with estimations based on accelerated laboratory-aging studies. Correlations for estimating thermal-aging degradation of cast stainless steels indicate that the degree of embrittlement of the Shippingport materials is low. The minimum room-temperature impact energies that would ever be achieved after long-term aging are >75 J/cm{sup 2} (>45 ft{center dot}lb) for all materials. The estimated activation energies for embrittlement range from 150 to 230 kJ/mole. The estimated fracture toughness J-R curves for the materials are also presented. 14 refs., 16 figs.

  9. Stainless Steel Round Robin Test: Centrifugally cast stainless steel screening phase

    SciTech Connect

    Bates, D.J.; Doctor, S.R.; Heasler, P.G.; Burck, E.

    1987-10-01

    This report presents the results of the Centrifugally Cast Stainless Steel Round Robin Test (CCSSRRT). The CCSSRRT is the first phase of an effort to investigate and improve the capability and reliability of NDE inspections of light water reactor piping systems. This phase was a screening test to identify the most promising procedures presently available for CCSS. The next phase will be an in-depth program to evaluate the capability and reliability of inservice inspections (ISI) for piping. In the CCSSRRT, 15 centrifugally cast stainless steel pipe sections containing welds and laboratory-grown thermal fatigue cracks in both columnar and equiaxed base material were used. These pipe specimens were inspected by a total of 18 teams from Europe and the United States using a variety of NDE techniques, mostly ultrasonic (UT). The inspections were carried out at the team's facilities and included inspections from both sides of the weld and inspections restricted to one side of the weld. The results of the CCSSRRT make it apparent that a more detailed study on the capability and reliability of procedures to inspect stainless steel materials is needed to better understand the specific material and flaw properties and how they affect the outcome of an inspection.

  10. Challenges and Capabilities for Inspection of Cast Stainless Steel Piping

    SciTech Connect

    Anderson, Michael T.; Crawford, Susan L.; Cumblidge, Stephen E.; Diaz, Aaron A.; Doctor, Steven R.

    2007-12-31

    Studies conducted at the Pacific N¬orthwest National Laboratory (PNNL) in Richland, Washington, have focused on developing and evaluating the reliability of nondestructive examination (NDE) approaches for inspecting coarse-grained, cast stainless steel reactor components. The objective of this work is to provide information to the United States Nuclear Regulatory Commission (US NRC) on the utility, effec¬tiveness and limitations of NDE techniques as related to the inservice inspec¬tion of primary system piping components in pressurized water reactors (PWRs). This paper describes results from recent assessments built upon early work with low frequency ultrasonic testing (UT) coupled with synthetic aperture focusing technique (SAFT) signal processing, and has subsequently evolved into an approach using low frequency phased array technology as applied from the outer diameter surface of the piping. In addition, eddy current examination as performed from the inner diameter surface of these piping welds is also reported. Cast stainless steel (CSS) pipe specimens were examined that contain thermal and mechanical fatigue cracks located close to the weld roots and have inside/outside surface geometrical conditions that simulate several PWR primary piping weldments and configurations. In addition, segments of vintage centrifugally cast piping were also examined to understand inherent acoustic noise and scattering due to grain structures and determine consistency of UT responses from different locations. The advanced UT methods were applied from the outside surface of these specimens using automated scanning devices and water coupling. The phased array approach was implemented with a modified instrument operating at low frequencies and composite volumetric images of the samples were generated with 500 kHz, 750 kHz, and 1.0 MHz arrays. Eddy current studies were conducted on the inner diameter surface of these piping welds using a commercially available instrument and a

  11. Hydrogen assisted cracking of 2205 duplex stainless steel in synthetic sea water

    NASA Astrophysics Data System (ADS)

    Michalska, J.; Łabanowski, J.; Ćwiek, J.

    2012-05-01

    The cracking behavior of 2205 duplex stainless steels (DSSs) in synthetic sea water under cathodic polarization condition was investigated. (SSRT) method was employed in aim to evaluate the susceptibility to hydrogen assisted cracking. The results showed that the reduction in the uniform elongation (UEL) and the reduction of area (RA) varied with the applied cathodic current density. Significant reductions in ductility were found, indicating its susceptibility to hydrogen-assisted fracture at current density of 10 mA cm-2. Fractographical examinations showed that increase in hydrogenation current density cause an increase in brittle character on the fracture surface. Complete brittle fractures were observed after SSRT at10 and 20 mA cm-2.

  12. Corrosion of 2205 Duplex Stainless Steel Weldment in Chloride Medium Containing Sulfate-Reducing Bacteria

    NASA Astrophysics Data System (ADS)

    Antony, P. J.; Singh Raman, R. K.; Kumar, Pradeep; Raman, R.

    2008-11-01

    Influence of changes in microstructure caused due to welding on microbiologically influenced corrosion of a duplex stainless steel was studied by exposing the weldment and parent metal to chloride medium containing sulfate-reducing bacteria (SRB). Identically prepared coupons (same area and surface finish) exposed to sterile medium were used as the control. Etching-type attack was observed in the presence of SRB, which was predominant in the heat-affected zone (HAZ) of the weldment. The anodic polarization studies indicated an increase in current density for coupon exposed to SRB-containing medium as compared to that obtained for coupon exposed to sterile medium. The scanning electron microscopy (SEM) observations after anodic polarization revealed that the attack was preferentially in the ferrite phase of HAZ of the weldment, whereas it was restricted to the austenite phase of the parent metal.

  13. Direct observations of sigma phase growth and dissolution in 2205 duplex stainless steel

    SciTech Connect

    Palmer, T.A.; Elmer, J.W.; Babu, S.S.; Specht, E.D.

    2007-10-10

    The formation and growth of sigma ({sigma}) phase in a 2205 duplex stainless steel is monitored during an 850 C isothermal heat treatment using an in situ synchrotron x-ray diffraction technique. At this temperature, {sigma} phase is first observed within approximately 40 seconds of the start of the isothermal heat treatment and grows rapidly over the course of the 3600 second heat treatment to a volume fraction of approximately 13%. A simultaneous increase in the austenite ({gamma}) volume fraction and a decrease in the ferrite ({delta}) volume fraction are observed. The {sigma} phase formed at this temperature is rapidly dissolved within approximately 200 seconds when the temperature is increased to 1000 C. Accompanying this rapid dissolution of the {sigma} phase, the {delta} and {gamma} volume fractions both approach the balanced (50/50) level observed in the as-received material.

  14. Direct Observations of Sigma Phase Growth and Dissolution in 2205 Duplex Stainless Steel

    SciTech Connect

    Palmer, T; Elmer, J; Babu, S; Specht, E

    2005-06-14

    The formation and growth of sigma ({sigma}) phase in a 2205 duplex stainless steel is monitored during an 850 C isothermal heat treatment using an in situ synchrotron x-ray diffraction technique. At this temperature, {sigma} phase is first observed within approximately 40 seconds of the start of the isothermal heat treatment and grows rapidly over the course of the 3600 second heat treatment to a volume fraction of approximately 13%. A simultaneous increase in the austenite ({gamma}) volume fraction and a decrease in the ferrite ({delta}) volume fraction are observed. The {sigma} phase formed at this temperature is rapidly dissolved within approximately 200 seconds when the temperature is increased to 1000 C. Accompanying this rapid dissolution of the {sigma} phase, the {delta} and {gamma} volume fractions both approach the balanced (50/50) level observed in the as-received material.

  15. Decomposition and Precipitation Process During Thermo-mechanical Fatigue of Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Weidner, Anja; Kolmorgen, Roman; Kubena, Ivo; Kulawinski, Dirk; Kruml, Tomas; Biermann, Horst

    2016-05-01

    The so-called 748 K (475 °C) embrittlement is one of the main drawbacks for the application of ferritic-austenitic duplex stainless steels (DSS) at higher temperatures caused by a spinodal decomposition of the ferritic phase. Thermo-mechanical fatigue tests performed on a DSS in the temperature range between 623 K and 873 K (350 °C and 600 °C) revealed no negative influence on the fatigue lifetime. However, an intensive subgrain formation occurred in the ferritic phase, which was accompanied by formation of fine precipitates. In order to study the decomposition process of the ferritic grains due to TMF testing, detailed investigations using scanning and transmission electron microscopy are presented. The nature of the precipitates was determined as the cubic face centered G-phase, which is characterized by an enrichment of Si, Mo, and Ni. Furthermore, the formation of secondary austenite within ferritic grains was observed.

  16. Corrosion performance of duplex and austenitic stainless steels in simulated SO{sub 2} absorber environments

    SciTech Connect

    Agrawal, A.K.; Koch, G.H.; Ross, R.W.

    1996-08-01

    The new generation of FGD systems are planned to operate in a near closed-loop mode to minimize waste discharge in order to meet the 1990 US Clean Air Act Amendments. Because of this closed-loop operation, the chloride concentration in the SO{sub 2} absorbers could build up as high as 100,000 ppm. Some duplex and 4--6% Mo containing stainless steels are candidate materials of construction for these absorbers. The corrosion behavior of some candidate alloys (Alloy 2205, Type 317LMN and 6% Mo stainless steels) has been investigated in simulated SO{sub 2} absorber environments. In addition to these alloys, Type 316L stainless steel and the nickel-base alloy C-276 were tested as reference alloys. Both welded and unwelded coupons of the alloys were exposed to calcium chloride brines having chloride concentrations of 10,000, 20,000, 30,000, 50,000, and 100,000 ppm at temperatures of 55 and 80 C. Alloy C-276 experienced only very light uniform attack with corrosion rates of less than 1.0 mpy. All the other alloys experienced significant corrosion attack under the scale deposits, some pitting of the base metal, and considerable localized attack in the heat affected zones adjacent to the welds. The overall performance of the alloys in the order of decreasing corrosion resistance was as follows: Alloy C-276 > 6% Mo stainless steel > Alloy 2205 > Type 317LMN > Type 316L. The temperature was a more significant variable in promoting corrosion of the alloys than was chloride concentration in the range investigated.

  17. Mechanism of hot-rolling crack formation in lean duplex stainless steel 2101

    NASA Astrophysics Data System (ADS)

    Feng, Zhi-hui; Li, Jing-yuan; Wang, Yi-de

    2016-04-01

    The thermoplasticity of duplex stainless steel 2205 (DSS2205) is better than that of lean duplex steel 2101 (LDX2101), which undergoes severe cracking during hot rolling. The microstructure, microhardness, phase ratio, and recrystallization dependence of the deformation compatibility of LDX2101 and DSS2205 were investigated using optical microscopy (OM), electron backscatter diffraction (EBSD), Thermo-Calc software, and transmission electron microscopy (TEM). The results showed that the phase-ratio transformations of LDX2101 and DSS2205 were almost equal under the condition of increasing solution temperature. Thus, the phase transformation was not the main cause for the hot plasticity difference of these two steels. The grain size of LDX2101 was substantially greater than that of DSS2205, and the microhardness difference of LDX2101 was larger than that of DSS2205. This difference hinders the transfer of strain from ferrite to austenite. In the rolling process, the ferrite grains of LDX2101 underwent continuous softening and were substantially refined. However, although little recrystallization occurred at the boundaries of austenite, serious deformation accumulated in the interior of austenite, leading to a substantial increase in hardness. The main cause of crack formation is the microhardness difference between ferrite and austenite.

  18. Characterization of microstructure and texture across dissimilar super duplex/austenitic stainless steel weldment joint by austenitic filler metal

    SciTech Connect

    Eghlimi, Abbas; Shamanian, Morteza; Eskandarian, Masoomeh; Zabolian, Azam; Szpunar, Jerzy A.

    2015-08-15

    The evolution of microstructure and texture across an as-welded dissimilar UNS S32750 super duplex/UNS S30403 austenitic stainless steel joint welded by UNS S30986 (AWS A5.9 ER309LMo) austenitic stainless steel filler metal using gas tungsten arc welding process was evaluated by optical micrography and EBSD techniques. Due to their fabrication through rolling process, both parent metals had texture components resulted from deformation and recrystallization. The weld metal showed the highest amount of residual strain and had large austenite grain colonies of similar orientations with little amounts of skeletal ferrite, both oriented preferentially in the < 001 > direction with cub-on-cube orientation relationship. While the super duplex stainless steel's heat affected zone contained higher ferrite than its parent metal, an excessive grain growth was observed at the austenitic stainless steel's counterpart. At both heat affected zones, austenite underwent some recrystallization and formed twin boundaries which led to an increase in the fraction of high angle boundaries as compared with the respective base metals. These regions showed the least amount of residual strain and highest amount of recrystallized austenite grains. Due to the static recrystallization, the fraction of low degree of fit (Σ) coincident site lattice boundaries, especially Σ3 boundaries, was increased in the austenitic stainless steel heat affected zone, while the formation of subgrains in the ferrite phase increased the content of < 5° low angle boundaries at that of the super duplex stainless steel. - Graphical abstract: Display Omitted - Highlights: • Extensive grain growth in the HAZ of austenitic stainless steel was observed. • Intensification of < 100 > orientated grains was observed adjacent to both fusion lines. • Annealing twins with Σ3 CSL boundaries were formed in the austenite of both HAZ. • Cub-on-cube OR was observed between austenite and ferrite in the weld metal.

  19. Sigma phase detection in duplex stainless steel by induced magnetic field

    NASA Astrophysics Data System (ADS)

    Silva, E. M.; Fialho, W. M. L.; Silva, H. F. B. M.; Leite, J. P.; Leite, J. P.; Oliveira, A. V. G.

    2016-07-01

    Duplex stainless steels when subjected to temperatures above 600 ° C have its tenacity decreased by the formation of sigma phase. This phase has high hardness and is rich in chromium and reduces the matrix of this element. In this study, field line density measurements, obtained in the reversibility region of magnetic domains, and application of artificial neural networks are used to monitor the formation of this undesirable phase. Samples of a stainless steel SAF 2205 were subjected to aging at temperatures of 800 ° C and 900 ° C, in order to obtain different amounts of sigma phase. The amount of this phase was obtained by image processing and the density of field lines through a Hall Effect sensor. Charpy impact tests were performed. The field lines densities were used for training of an artificial neural network and correlated with the presence of sigma phase and embrittlement of the material. The results showed that the method was able to correlate the parameters studied with the presence of the sigma phase and toughness of the material studied in both temperatures.

  20. In situ neutron diffraction study of the low cycle fatigue of the α-γ duplex stainless steel

    NASA Astrophysics Data System (ADS)

    Jenčuš, Peter; Polák, Jaroslav; Lukáš, Petr; Muránsky, Ondrej

    2006-11-01

    In duplex stainless steels, significant thermal stresses are generated during the cooling from the homogenization temperature due to different thermal expansion coefficients of the austenitic and ferritic phases. The results of the in situ neutron diffraction examination of the evolution of the internal stresses during the low cycle fatigue in the SAF 2507 duplex stainless steel are reported. Stress response of both constituent components resulting from the load sharing between austenitic and ferritic grains was measured. It was found that the initial thermal residual stresses were relaxed rapidly at the beginning of the cyclic loading. Whereas initial hardening was identified in both phases, the subsequent fatigue softening was fully attributed to the austenitic phase.

  1. Comparison of duplex to austenitic stainless steels for DOT 407 and 412 cargo tanks in liquid chemical service

    SciTech Connect

    Staebler, R.R.

    1998-12-31

    U.S. Highway transportation of liquid chemicals has depended upon austenitic stainless steels (316 and 304) since the 1940`s. This paper will compare these austenitics to the duplex stainless steels (UNS S31803 and S32205 both commonly known as 2205 and UNS S32304 commonly known as 2304) from various aspects such as: composition, mechanical and physical properties; corrosion resistance; design, manufacturing and welding of vessel; heating panel application on the bottom of the vessel; surface finish; DOT Regulations; and cost. Some actual experience with 2205 will be explained.

  2. Investigation of corrosion of welded joints of austenitic and duplex stainless steels

    NASA Astrophysics Data System (ADS)

    Topolska, S.

    2016-08-01

    Investigation of corrosion resistance of materials is one of the most important tests that allow determining their functional properties. Among these tests the special group consist electrochemical investigations, which let to accelerate the course of the process. These investigations allow rapidly estimating corrosion processes occurring in metal elements under the influence of the analysed environment. In the paper are presented results of investigations of the resistance to pitting corrosion of the steel of next grades: austenitic 316L and duplex 2205. It was also analysed the corrosion resistance of welded joints of these grades of steel. The investigations were conducted in two different corrosion environments: in the neutral one (3.5 % sodium chloride) and in the aggressive one (0.1 M sulphuric acid VI). The obtained results indicate different resistance of analysed grades of steel and their welded joints in relation to the corrosion environment. The austenitic 316L steel characterizes by the higher resistance to the pitting corrosion in the aggressive environment then the duplex 2205 steel. In the paper are presented results of potentiodynamic tests. They showed that all the specimens are less resistant to pitting corrosion in the environment of sulphuric acid (VI) than in the sodium chloride one. The 2205 steel has higher corrosion resistance than the 316L stainless steel in 3.5% NaCl. On the other hand, in 0.1 M H2SO4, the 316L steel has a higher corrosion resistance than the 2205 one. The weld has a similar, very good resistance to pitting corrosion like both steels.

  3. Assessment of thermal embrittlement in duplex stainless steels 2003 and 2205 for nuclear power applications

    DOE PAGES

    Tucker, J. D.; Miller, M. K.; Young, G. A.

    2015-04-01

    Duplex stainless steels are desirable for use in power generation systems due to their attractive combination of strength, corrosion resistance, and cost. However, thermal embrittlement at intermediate homologous temperatures of ~887°F (475°C) and below, via spinodal decomposition, limits upper service temperatures for many applications. New lean grade duplex alloys have improved thermal stability over standard grades and potentially increase the upper service temperature or the lifetime at a given temperature for this class of material. The present work compares the thermal stability of lean grade, alloy 2003 to standard grade, alloy 2205, through a series of isothermal agings between 500°Fmore » (260°C) and 900°F (482°C) for times between 1 and 10,000 hours. Aged samples were characterized by changes in microhardness and impact toughness. Additionally, atom probe tomography was performed to illustrate the evolution of the α-α' phase separation in both alloys at select conditions. Atom probe tomography confirmed that phase separation occurs via spinodal decomposition for both alloys and identified the formation of Ni-Cu-Si-Mn-P clusters in alloy 2205 that may contribute to embrittlement of this alloy. The impact toughness model predictions for upper service temperature show that alloy 2003 can be considered for use in 550°F applications for 80 year service lifetimes based on a Charpy V-notch criteria of 35 ft-lbs at 70°F. Alloy 2205 should be limited to 500°F applications.« less

  4. Assessment of thermal embrittlement in duplex stainless steels 2003 and 2205 for nuclear power applications

    SciTech Connect

    Tucker, J. D.; Miller, M. K.; Young, G. A.

    2015-04-01

    Duplex stainless steels are desirable for use in power generation systems due to their attractive combination of strength, corrosion resistance, and cost. However, thermal embrittlement at intermediate homologous temperatures of ~887°F (475°C) and below, via spinodal decomposition, limits upper service temperatures for many applications. New lean grade duplex alloys have improved thermal stability over standard grades and potentially increase the upper service temperature or the lifetime at a given temperature for this class of material. The present work compares the thermal stability of lean grade, alloy 2003 to standard grade, alloy 2205, through a series of isothermal agings between 500°F (260°C) and 900°F (482°C) for times between 1 and 10,000 hours. Aged samples were characterized by changes in microhardness and impact toughness. Additionally, atom probe tomography was performed to illustrate the evolution of the α-α' phase separation in both alloys at select conditions. Atom probe tomography confirmed that phase separation occurs via spinodal decomposition for both alloys and identified the formation of Ni-Cu-Si-Mn-P clusters in alloy 2205 that may contribute to embrittlement of this alloy. The impact toughness model predictions for upper service temperature show that alloy 2003 can be considered for use in 550°F applications for 80 year service lifetimes based on a Charpy V-notch criteria of 35 ft-lbs at 70°F. Alloy 2205 should be limited to 500°F applications.

  5. Effect of gadolinium addition on the corrosion, wear, and neutron absorbing behaviors of duplex stainless steel sheet

    NASA Astrophysics Data System (ADS)

    Baik, Youl; Choi, Yong; Moon, Byung M.; Sohn, Dong S.; Bogdanov, S. G.; Pirogov, A. N.

    2015-11-01

    In order to develop the neutron absorbing and shield materials, a hot-rolled 0.02%-Gd duplex stainless steel was prepared with 55 vol. % of ferrite and 45 vol. % of austenite. The σ phase with an average grain size of 9-11 μm in austenitic (γ) grains tended to be elongated parallel to the rolling direction, with (100) poles concentrated towards the normal direction, and (110) poles located between the normal and radial directions (ND and RD, respectively). Most of the gadolinium existed as sub-micro-meter-sized Gd2O3 and GdCrO3 precipitates. The yield strength, ultimate tensile strength, elongation, and microhardness of the 0.02%-Gd duplex stainless steel were 522.8 MPa, 700.2 MPa, 38.1%, and 258.5-314.7 HV, respectively. The friction coefficient and wear resistance were 3.11 and 0.004 mg/kg/cycle, respectively. The corrosion potential and corrosion rate of the 0.02%-Gd duplex stainless steel were-0.448 V SHE and 1.263 × 10-3 A/cm2 for 1M-HCl,-0.544 V SHE and 2.619 × 10-3 A/cm2 for 1M-NaCl,-0.299 V SHE and 1.469 × 10-3 A/cm2 for 1M-H2SO4, and-0.607 V SHE and 2.295 × 10-3 A/cm2 for synthetic water, respectively. The coefficient of neutron transmission for the 0.02%-Gd duplex stainless steel sheet of 2 mm thickness at neutron beam wavelength of 0.48 nm was 0.6.

  6. A process model for the heat-affected zone microstructure evolution in duplex stainless steel weldments: Part I. The model

    SciTech Connect

    Hemmer, H.; Grong, O.

    1999-11-01

    The present investigation is concerned with modeling of the microstructure evolution in duplex stainless steels under thermal conditions applicable to welding. The important reactions that have been modeled are the dissolution of austenite during heating, subsequent grain growth in the delta ferrite regime, and finally, the decomposition of the delta ferrite to austenite during cooling. As a starting point, a differential formulation of the underlying diffusion problem is presented, based on the internal-state variable approach. These solutions are later manipulated and expressed in terms of the Scheil integral in the cases where the evolution equation is separable or can be made separable by a simple change of variables. The models have then been applied to describe the heat-affected zone microstructure evolution during both thick-plate and thin-plate welding of three commercial duplex stainless steel grades: 2205, 2304, and 2507. The results may conveniently be presented in the form of novel process diagrams, which display contours of constant delta ferrite grain size along with information about dissolution and reprecipitation of austenite for different combinations of weld input energy and peak temperature. These diagrams are well suited for quantitative readings and illustrate, in a condensed manner, the competition between the different variables that lead to structural changes during welding of duplex stainless steels.

  7. A process model for the heat-affected zone microstructure evolution in duplex stainless steel weldments: Part I. the model

    NASA Astrophysics Data System (ADS)

    Hemmer, H.; Grong, Ø.

    1999-11-01

    The present investigation is concerned with modeling of the microstructure evolution in duplex stainless steels under thermal conditions applicable to welding. The important reactions that have been modeled are the dissolution of austenite during heating, subsequent grain growth in the delta ferrite regime, and finally, the decomposition of the delta ferrite to austenite during cooling. As a starting point, a differential formulation of the underlying diffusion problem is presented, based on the internal-state variable approach. These solutions are later manipulated and expressed in terms of the Scheil integral in the cases where the evolution equation is separable or can be made separable by a simple change of variables. The models have then been applied to describe the heat-affected zone microstructure evolution during both thick-plate and thin-plate welding of three commercial duplex stainless steel grades: 2205, 2304, and 2507. The results may conveniently be presented in the form of novel process diagrams, which display contours of constant delta ferrite grain size along with information about dissolution and reprecipitation of austenite for different combinations of weld input energy and peak temperature. These diagrams are well suited for quantitative readings and illustrate, in a condensed manner, the competition between the different variables that lead to structural changes during welding of duplex stainless steels.

  8. The Induction of Hyperthermia in Rabbit Liver by means of Duplex Stainless Steel Thermoseeds

    PubMed Central

    Koo, Bong Sig; Kim, Young Kon; Kim, Moon Kon

    2002-01-01

    Objective To determine the heating characteristics of needle-shaped duplex stainless steel thermoseeds, and to evaluate their effectiveness in the induction of hyperthermia in rabbit liver. Materials and Methods Thermoseeds of the two different shapes, L-shaped for single doses of hyperthermia and I-shaped for in-vitro study and repeated hyperthermic induction, were prepared. For the in-vitro study, an I-shaped thermoseed 0.23 mm in diameter and 25 mm long was placed inside a plastic tube filled with water. Heat was applied for 30 minutes within an induction magnetic field, and during this time changes in temperature were recorded using three thermocouples. For the in-vivo study, fifteen New Zealand white rabbits were divided into five equal groups. An I-shaped or L-shaped thermoseed was inserted in each rabbit's liver, and then placed within the center of the magnetic induction coil during a 30-minute period of hyperthermia. The rabbits in the first group were sacrificed immediately after hyperthermia was induced once, while those in the other groups were sacrificed at 1, 3, and 7 days, respectively, also after one induction. The remaining three rabbits were sacrificed 4 days after three consecutive daily treatment sessions. The resected segments of liver were subsequently evaluated histopathologically for the extent of coagulation necrosis caused by heating of the thermoseed. Results The in-vitro study demonstrated that the temperature in the thermoseed, which was 25.9℃ before heating and 54.8℃ after heating, rose rapidly at first but progressively less rapidly as time elapsed. Light microscopic examination of the rabbits' livers revealed coagulation necrosis and infiltration by inflammatory cells around the insertion site of the thermoseed. The maximum diameter of coagulation necrosis was 2.81 ± 1.68 mm, and this occurred in the rabbits that were sacrificed 7 days after heat induction. Conclusion Needle-shaped duplex stainless steel thermoseeds show

  9. Effect of solution annealing temperature on precipitation in 2205 duplex stainless steel

    SciTech Connect

    Kashiwar, A.; Vennela, N. Phani; Kamath, S.L.; Khatirkar, R.K.

    2012-12-15

    In the present study, effect of solution annealing temperature (1050 Degree-Sign C and 1100 Degree-Sign C) and isothermal ageing (700 Degree-Sign C: 15 min to 6 h) on the microstructural changes in 2205 duplex stainless steel has been investigated systematically. Scanning electron microscopy and X-ray diffraction were adopted to follow the microstructural evolution, while an energy dispersive spectrometer attached to scanning electron microscope was used to obtain localised chemical information of various phases. The ferritic matrix of the two phase 2205 duplex stainless steel ({approx} 45% ferrite and {approx} 55% austenite) undergoes a series of metallurgical transformations during ageing-formation of secondary austenite ({gamma}{sub 2}) and precipitation of Cr and Mo rich intermetallic (chi-{chi} and sigma-{sigma}) phases. For solution annealing at 1050 Degree-Sign C, significant amount of carbides were observed in the ferrite grains after 1 h of ageing at 700 Degree-Sign C. {chi} Phase precipitated after the precipitation of carbides-preferentially at the ferrite-ferrite and also at the ferrite-austenite boundaries. {sigma} Phase was not observed in significant quantity even after 6 h of ageing. The sequence of precipitation in samples solution annealed at 1050 Degree-Sign C was found to be carbides {yields} {chi} {yields} {sigma}. On the contrary, for samples solution annealed at 1100 Degree-Sign C, the precipitation of {chi} phase was negligible. {chi} Phase precipitated before {sigma} phase, preferentially along the ferrite-ferrite grain boundaries and was later consumed in the {sigma} phase precipitation. The {sigma} phase precipitated via the eutectoid transformation of ferrite to yield secondary austenite {gamma}{sub 2} and {sigma} phase in the ferrite and along the ferrite-austenite grain boundaries. An increase in the volume fraction of {gamma}{sub 2} and {sigma} phase with simultaneous decrease in the ferrite was evidenced with ageing. - Highlights

  10. Hardness analysis of welded joints of austenitic and duplex stainless steels

    NASA Astrophysics Data System (ADS)

    Topolska, S.

    2016-08-01

    Stainless steels are widely used in the modern world. The continuous increase in the use of stainless steels is caused by getting greater requirements relating the corrosion resistance of all types of devices. The main property of these steels is the ability to overlap a passive layer of an oxide on their surface. This layer causes that they become resistant to oxidation. One of types of corrosion-resistant steels is ferritic-austenitic steel of the duplex type, which has good strength properties. It is easily formable and weldable as well as resistant to erosion and abrasive wear. It has a low susceptibility to stress-corrosion cracking, to stress corrosion, to intercrystalline one, to pitting one and to crevice one. For these reasons they are used, among others, in the construction of devices and facilities designed for chemicals transportation and for petroleum and natural gas extraction. The paper presents the results which shows that the particular specimens of the ][joint representing both heat affected zones (from the side of the 2205 steel and the 316L one) and the weld are characterized by higher hardness values than in the case of the same specimens for the 2Y joint. Probably this is caused by machining of edges of the sections of metal sheets before the welding process, which came to better mixing of native materials and the filler metal. After submerged arc welding the 2205 steel still retains the diphase, austenitic-ferritic structure and the 316L steel retains the austenitic structure with sparse bands of ferrite σ.

  11. Evaluation of aging of cast stainless steel components

    SciTech Connect

    Chung, H.M.

    1991-02-01

    Cast stainless steel is used extensively in nuclear reactors for primary-pressure-boundary components such as primary coolant pipes, elbows, valves, pumps, and safe ends. These components are, however, susceptible to thermal aging embrittlement in light water reactors because of the segregation of Cr atoms from Fe and Ni by spinodal decomposition in ferrite and the precipitation of Cr-rich carbides on ferrite/austenite boundaries. A recent advance in understanding the aging kinetics is presented. Aging kinetics are strongly influenced by the synergistic effects of other metallurgical reactions that occur in parallel with spinodal decomposition, i.e., clustering of Ni, Mo, and Si solute atoms and the nucleation and growth of G-phase precipitates in the ferrite phase. A number of methods are outlined for estimating aging embrittlement under end-of-life of life-extension conditions, depending on several factors such as degree of permissible conservatism, availability of component archive material, and methods of estimating and verifying the activation energy of aging. 33 refs., 6 figs., 3 tabs.

  12. In-situ Characterization of Cast Stainless Steel Microstructures

    SciTech Connect

    Ramuhalli, Pradeep; Meyer, Ryan M.; Cinson, Anthony D.; Moran, Traci L.; Prowant, Matthew S.; Watson, Bruce E.; Mathews, Royce; Harris, Robert V.; Diaz, Aaron A.; Anderson, Michael T.

    2012-09-01

    Cast austenitic stainless steel (CASS) was commonly used in selected designs of nuclear power reactor systems for corrosion resistance and enhanced durability in service. CASS materials are generally coarse-grained and elastically anisotropic in nature, and are consequently difficult to inspect ultrasonically, largely due to detrimental effects of ultrasonic wave interactions with the coarse-grain microstructures. To address the inspection needs for these materials, new approaches that are robust to these phenomena are being developed. However, to enhance the probability of detecting flaws, knowledge of the microstructure and the corresponding acoustic properties of the material may be required. This paper discusses the application of ultrasonic backscatter measurement methods for classifying the microstructure of CASS components, when making measurements from the outside surface of the pipe or component. Results to date from laboratory experiments demonstrate the potential of these measurements to classify the material type of CASS for two homogeneous microstructures—equiaxed-grain material or columnar-grain material. Measurements on mixed or banded microstructures also show correlation with the estimated volume-fraction of columnar grains in the material. However, several operational issues will need to be addressed prior to applying this method for in-situ characterization of CASS microstructure.

  13. In-situ Characterization of Cast Stainless Steel Microstructures

    SciTech Connect

    Anderson, Michael T.; Bond, Leonard J.; Diaz, Aaron A.; Good, Morris S.; Harris, Robert V.; Mathews, Royce; Ramuhalli, Pradeep; Roberts, Kamandi C.

    2010-12-01

    Cast austenitic stainless steel (CASS) that was commonly used in U.S. nuclear power plants is a coarse-grained, elastically anisotropic material. The engineering properties of CASS made it a material of choice for selected designs of nuclear power reactor systems. However, the fabrication processes result in a variety of coarse-grain microstructures that are difficult to inspect ultrasonically, largely due to detrimental effects of wave interactions with the microstructure. To address the inspection needs, new approaches that are robust to these phenomena are being sought. However, overcoming the deleterious effects of the coarse-grained microstructure on the interrogating ultrasonic beam will require knowledge of the microstructure and the corresponding acoustic properties of the material, for potential optimization of inspection parameters to enhance the probability of detecting flaws. The goal of improving the reliability and effectiveness of ultrasonic inspection of CASS specimens can therefore potentially be achieved by first characterizing the microstructure of the component. The characterization of CASS microstructure must be done in-situ, to enable dynamic selection and optimization of the ultrasonic inspection technique. This paper discusses the application of ultrasonic measurement methods for classifying the microstructure of CASS components, when making measurements from the outside surface of the pipe or component. Results to date demonstrate the potential of ultrasonic and electromagnetic measurements to classify the material type of CASS for two consistent microstructures-equiaxed-grain material and columnar-grain material.

  14. Studies of aged cast stainless steel from the Shippingport reactor

    SciTech Connect

    Chopra, O.K.

    1991-10-01

    The mechanical properties of cast stainless steels from the Shippingport reactor have been characterized. Baseline properties for unaged materials were obtained from tests on either recovery-annealed material or material from a cooler region of the component. The materials exhibited modest decrease in impact energy and fracture toughness and a small increase in tensile strength. The fracture toughness J-R curve, J{sub IC} value, tensile flow stress, and Charpy-impact energy of the materials showed very good agreement with estimations based on accelerated laboratory aging studies. The kinetics of thermal embrittlement and degree of embrittlement at saturation, i.e., the minimum impact energy that would be achieved after long-term aging, were established from materials that were aged further in the laboratory at temperatures between 320 and 400{degree}C. The results showed very good agreement with estimates; the activation energies ranged from 125 to 250 kJ/mole and the minimum room-temperature impact energy was >75 J/cm{sup 2}. The estimated impact energy and fracture toughness J-R curve for materials from the Ringhals reactor hot and crossover-leg elbows are also presented.

  15. Effect of Aging on the Fracture Behavior of Lean Duplex Stainless Steels

    NASA Astrophysics Data System (ADS)

    Straffelini, G.; Baldo, S.; Calliari, I.; Ramous, E.

    2009-11-01

    The influence of aging in the range of 550 °C to 850 °C for 5 to 120 minutes on the impact fracture behavior of 2101 and 2304 lean duplex stainless steels (DSS) was investigated in the present study. The 2304 steel displayed ductile behavior irrespective of aging conditions. In contrast, the 2101 steel displayed a ductile behavior only in the case of aging for 5 minutes at 550 °C and 650 °C, whereas in all other cases, it fractured in a brittle manner. The brittle fracture behavior of the 2101 steel has been attributed to the precipitation of small black particles at the α/ α and α/ γ grain boundaries (nitrides), which form paths for easy crack propagation. In the 2304 steel, such particles precipitated at 750 °C and 850 °C, but they were located inside the austenitic grains because of the formation of secondary austenite. They therefore did not embrittle the steel. The larger Ni content of the 2304 steel favored the formation of the secondary austenite that is absent in the 2101 steel.

  16. Delaminations by Cleavage Cracking in Duplex Stainless Steels at Sub-zero Temperatures

    NASA Astrophysics Data System (ADS)

    Pilhagen, Johan; Sandström, Rolf

    2013-10-01

    Impact toughness testing was conducted on 10 and 30 mm plates of 2205 together with a 30 mm plate of LDX 2101® duplex stainless steel (DSS). The testing temperatures were between 153 K (-120 °C) and room temperature. Interrupted fracture toughness tests of the 10 mm plate and a 50 mm plate of 2205 were also performed. The conclusion from the fractographic investigation was that the delaminations that occur in hot-rolled DSSs were cleavage fractures. The toughness anisotropy can be explained by the cleavage fracture and the appearance of the microstructure. The result from the interrupted fracture toughness test revealed that the delaminations initiated prior to the maximum force plateau and propagated ahead of the stable crack growth during testing. Estimated upper limit for the fracture delamination initiation toughness at sub-zero temperatures for the 2205 base metal according to the crack-tip opening displacement method was 28 to 61 μm for the 10 mm plate, 70 to 106 μm for the 30 mm plate and below 100 μm for the 50 mm plate.

  17. Effect of silver on microstructure and antibacterial property of 2205 duplex stainless steel.

    PubMed

    Yang, Sheng-Min; Chen, Yi-Chun; Pan, Yeong-Tsuen; Lin, Dong-Yih

    2016-06-01

    In this study, 2205 duplex stainless steel (DSS) was employed to enhance the antibacterial properties of material through silver doping. The results demonstrated that silver-doped 2205 DSS produces an excellent bacteria-inhibiting effect against Escherichia coli and Staphylococcus aureus. The antibacterial rates were 100% and 99.5%, respectively. Because the mutual solubility of silver and iron is very low in both the solid and liquid states, a silver-rich compound solidified and dispersed at the ferrite/austenite interface and the ferrite, austenite, and secondary austenite phases in silver-doped 2205 DSS. Doping 2205 DSS with silver caused the Creq/Nieq ratio of ferrite to decrease; however, the lower Creq/Nieq ratio promoted the rapid nucleation of γ2-austenite from primary α-ferrite. After 12h of homogenisation treatment at 1200 °C, the solubility of silver in the γ-austenite and α-ferrite phases can be increased by 0.10% and 0.09%, respectively. Moreover, silver doping was found to accelerate the dissolution of secondary austenite in a ferrite matrix during homogenisation. PMID:27040232

  18. SnO2:F Coated Duplex Stainless Steel for PEM Fuel Cell Bipolar Plates

    SciTech Connect

    Wang, H.; Turner, J. A.

    2008-01-01

    Duplex 2205 stainless steel was deposited with 0.6 {micro}m thick SnO2:F coating; coated steel was characterized for PEMFC bipolar plate application. Compared with bare alloy, interfacial contact resistance (ICR) values of the coated 2205 steel are higher. SnO2:F coating adds its own resistance to the air-formed film on the steel. In a PEMFC anode environment, a current peak of ca. 25 {micro}A/cm2 registered at ca. 30 min for coated 2205 steel. It stabilized at ca. 2.0 {approx} -1.0 {micro}A/cm2. This peak is related to the complicated process of coating dissolution and oxide-layer formation. Anodic-cathodic current transfer occurred at ca. 200 min polarization. In a PEMFC cathode environment, current was stable immediately after polarization. The stable current was ca. 0.5 {approx} 2.0 {micro}A/cm2 during the entire polarization period. AES depth profiles with tested samples and ICP analysis with the tested solutions confirmed the excellent corrosion resistance of the SnO2:F coated 2205 alloy in simulated PEMFC environments.

  19. Phase transformation and mechanical behavior in annealed 2205 duplex stainless steel welds

    SciTech Connect

    Badji, Riad Bouabdallah, Mabrouk; Bacroix, Brigitte; Kahloun, Charlie; Belkessa, Brahim; Maza, Halim

    2008-04-15

    The phase transformations and mechanical behaviour during welding and subsequent annealing treatment of 2205 duplex stainless steel have been investigated. Detailed microstructural examination showed the presence of higher ferrite amounts in the heat affected zone (HAZ), while higher amounts of austenite were recorded in the centre region of the weld metal. Annealing treatments in the temperature range of 800-1000 deg. C resulted in a precipitation of {sigma} phase and M{sub 23}C{sub 6} chromium carbides at the {gamma}/{delta} interfaces that were found to be preferential precipitation sites. Above 1050 deg. C, the volume fraction of {delta} ferrite increases with annealing temperature. The increase of {delta} ferrite occurs at a faster rate in the HAZ than in the base metal and fusion zone. Optimal mechanical properties and an acceptable ferrite/austenite ratio throughout the weld regions corresponds to annealing at 1050 deg. C. Fractographic examinations showed that the mode of failure changed from quasi-cleavage fracture to dimple rupture with an increase in the annealing temperature from 850 to 1050 deg. C.

  20. Automatic assessment of a two-phase structure in the duplex stainless-steel SAF 2205

    SciTech Connect

    Komenda, J. ); Sandstroem, R. )

    1993-10-01

    Automatic image analysis was used to study the effect of deformation on the size and distribution of the austenite and ferrite phases in the duplex stainless steel SAF 2205 (22Cr-5Ni-3Mo-15N). The main parameters used were the chord size to characterize the ferrite phase and Feret's diameter for the austenite phase. As the deformation increased, ferrite bands became more elongated and thinner, contributing to a pronounced banding. The amount of banding can be quantified by using a ratio between the slopes of the chord size distributions in the longitudinal and short transverse directions. According to a proposed model of the influence of deformation on the two-phase structure, the process of austenite elongation and subdivision of austenite islands (crushing) is described. The effect of deformation on the yield and tensile strength was expressed using a Hall-Petch type relationship where the grain size was represented by the average width of the ferrite bands. The observed anisotropy in strength properties is believed to be due to texture hardening. Because elongation at a given strength level is the same in both the longitudinal and transverse directions, the banding itself does not influence the ductility. Nor can the strength anisotropy be due to banding, because the strength is greater in the longitudinal than in the transverse direction.

  1. Mechanical Properties of Super Duplex Stainless Steel 2507 after Gas Phase Thermal Precharging with Hydrogen

    NASA Astrophysics Data System (ADS)

    San Marchi, C.; Somerday, B. P.; Zelinski, J.; Tang, X.; Schiroky, G. H.

    2007-11-01

    Thermal precharging of super duplex stainless steel 2507 with 125 wppm hydrogen significantly reduced tensile ductility and fracture toughness. Strain-hardened 2507 exhibited more severe ductility loss compared to the annealed microstructure. The reduction of area (RA) was between 80 and 85 pct for both microstructures in the noncharged condition, while reductions of area were 25 and 46 pct for the strain-hardened and annealed microstructures, respectively, after hydrogen precharging. Similar to the effect of internal hydrogen on tensile ductility, fracture toughness of strain-hardened 2507 was lowered from nearly 300 MPa m1/2 in the noncharged condition to less than 60 MPa m1/2 in the hydrogen-precharged condition. While precharging 2507 with hydrogen results in a considerable reduction in ductility and toughness, the absolute values are similar to high-strength austenitic steels that have been tested under the same conditions, and which are generally considered acceptable for high-pressure hydrogen gas systems. The fracture mode in hydrogen-precharged 2507 involved cleavage cracking of the ferrite phase and ductile fracture along oblique planes in the austenite phase, compared to 100 pct microvoid coalescence in the absence of hydrogen. Predictions from a strain-based micromechanical fracture toughness model were in good agreement with the measured fracture toughness of hydrogen-precharged 2507, implying a governing role of austenite for resistance to hydrogen-assisted fracture.

  2. Synchrotron Based Observations of Sigma Phase Formation and Dissolution in Duplex Stainless Steel

    SciTech Connect

    Elmer, J; Palmer, T; Specht, E

    2006-08-22

    The formation and growth of sigma ({sigma}) phase in 2205 duplex stainless steel was observed and measured in real time using synchrotron radiation during isothermal heat treating at temperatures between 700 C and 850 C. Synchrotron experiments were performed on this material at the Advanced Photon Source (APS) while isothermally holding the samples for times of up to 10 hr. During the isothermal hold, sigma formed in quantities up to 22% as the ferrite transformed to a mixture of sigma and austenite phases. In addition, sigma formed at 850 C was heated to 1000 C to observe its dissolution. The amounts of sigma that formed, and the dissolution temperature of sigma were compared to the results predicted by Thermocalc, showing differences between the calculated and measured values. The synchrotron data was further modeled using a modified Johnson-Mehl-Avrami analysis to determine kinetic parameters for sigma formation. The initial JMA exponent, n, at low fractions of sigma was found to be approximately 7.0, however, towards the end of the transformation, n decreased to values of approximately 0.75. Because of the variable value of n, it was not possible to determine reliable values for the activation energy and pre-exponential terms for the JMA equation. During cooling to room temperature, the high temperature austenite partially transformed to ferrite, substantially increasing the ferrite content while the sigma phase kept its high temperature value.

  3. Effect of process parameters on metal transfer of hyperbaric GMAW of duplex stainless steels

    SciTech Connect

    Olsen, J.M.; Dos Santos, J.F.; Richardson, I.M.

    1994-12-31

    This work presents the preliminary results of a comprehensive and systematic evaluation of current rise and fall rates as well as shielding gas composition and their affect on the metal transfer, when duplex stainless steels are GMA welded under hyperbaric conditions using the short circuit metal transfer mode. The evaluation of the test results are based on an examination of the welding process signals recorded on a transient recorder. Over a time period of 500 ms, the signal was measured to assess the process instability, current rise and fall rates and their inter-relationship. The results presented in this study indicate that for a given welding condition, the appropriate selection of current rise and fall rates can minimize the effect of instabilities caused by high ambient pressure. The presence of active gases in the shielding did not significantly affect the metal transfer behavior. All the experiments described in this work have been carried out in the hyperbaric test facilities of the GKSS-Forschungszentrum in Germany.

  4. Microbiologically Influenced Corrosion of 2707 Hyper-Duplex Stainless Steel by Marine Pseudomonas aeruginosa Biofilm

    PubMed Central

    Li, Huabing; Zhou, Enze; Zhang, Dawei; Xu, Dake; Xia, Jin; Yang, Chunguang; Feng, Hao; Jiang, Zhouhua; Li, Xiaogang; Gu, Tingyue; Yang, Ke

    2016-01-01

    Microbiologically Influenced Corrosion (MIC) is a serious problem in many industries because it causes huge economic losses. Due to its excellent resistance to chemical corrosion, 2707 hyper duplex stainless steel (2707 HDSS) has been used in the marine environment. However, its resistance to MIC was not experimentally proven. In this study, the MIC behavior of 2707 HDSS caused by the marine aerobe Pseudomonas aeruginosa was investigated. Electrochemical analyses demonstrated a positive shift in the corrosion potential and an increase in the corrosion current density in the presence of the P. aeruginosa biofilm in the 2216E medium. X-ray photoelectron spectroscopy (XPS) analysis results showed a decrease in Cr content on the coupon surface beneath the biofilm. The pit imaging analysis showed that the P. aeruginosa biofilm caused a largest pit depth of 0.69 μm in 14 days of incubation. Although this was quite small, it indicated that 2707 HDSS was not completely immune to MIC by the P. aeruginosa biofilm. PMID:26846970

  5. Evolutions of Microstructure and Properties During Cold Rolling of 19Cr Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Ran, Qingxuan; Xu, Wanjian; Wu, Zhaoyu; Li, Jun; Xu, Yulai; Xiao, Xueshan; Hu, Jincheng; Jiang, Laizhu

    2016-07-01

    Evolutions of microstructure, mechanical, and corrosion properties of 19Cr (Fe-18.9Cr-10.1Mn-0.3Ni-0.261N-0.030C-0.5Si) duplex stainless steel have been investigated during cold rolling at room temperature. Dislocation slip dominated deformation mode of ferrite phase. However, deformation mechanism of austenite phase was different with the increasing cold-rolling reductions. Dislocation slip and strengthening effect of twin boundaries caused pile-up phenomenon at the initial deformation stage. When the amount of cold-rolling reduction attained greater than 50 pct, induced α'-martensite appeared in deformed austenite phase. Hardness of austenite phase was higher than that of the deformed ferrite because of its higher strengthening effect during cold-rolling process. Cold-rolling deformation caused deterioration of the pitting corrosion resistance in 3.5 wt pct NaCl aqueous solution. Pitting corrosion always initiated in the ferrite phase and the phase boundary in the solution-treated alloy. Additional pitting holes appeared in deformed austenite phase because of the decrease in corrosion resistance caused by dislocation accumulation and induced α'-martensite.

  6. Microbiologically Influenced Corrosion of 2707 Hyper-Duplex Stainless Steel by Marine Pseudomonas aeruginosa Biofilm

    NASA Astrophysics Data System (ADS)

    Li, Huabing; Zhou, Enze; Zhang, Dawei; Xu, Dake; Xia, Jin; Yang, Chunguang; Feng, Hao; Jiang, Zhouhua; Li, Xiaogang; Gu, Tingyue; Yang, Ke

    2016-02-01

    Microbiologically Influenced Corrosion (MIC) is a serious problem in many industries because it causes huge economic losses. Due to its excellent resistance to chemical corrosion, 2707 hyper duplex stainless steel (2707 HDSS) has been used in the marine environment. However, its resistance to MIC was not experimentally proven. In this study, the MIC behavior of 2707 HDSS caused by the marine aerobe Pseudomonas aeruginosa was investigated. Electrochemical analyses demonstrated a positive shift in the corrosion potential and an increase in the corrosion current density in the presence of the P. aeruginosa biofilm in the 2216E medium. X-ray photoelectron spectroscopy (XPS) analysis results showed a decrease in Cr content on the coupon surface beneath the biofilm. The pit imaging analysis showed that the P. aeruginosa biofilm caused a largest pit depth of 0.69 μm in 14 days of incubation. Although this was quite small, it indicated that 2707 HDSS was not completely immune to MIC by the P. aeruginosa biofilm.

  7. Precipitation and Phase Transformations in 2101 Lean Duplex Stainless Steel During Isothermal Aging

    NASA Astrophysics Data System (ADS)

    Maetz, Jean-Yves; Cazottes, Sophie; Verdu, Catherine; Kleber, Xavier

    2016-01-01

    The effect of isothermal aging at 963 K (690 °C) on the microstructure of a 2101 lean duplex stainless steel, with the composition Fe-21.5Cr-5Mn-1.6Ni-0.22N-0.3Mo, was investigated using a multi-technique and multi-scale approach. The kinetics of phase transformation and precipitation was followed from a few minutes to thousands of hours using thermoelectric power measurements; based on these results, certain aging states were selected for electron microscopy characterization. Scanning electron microscopy, electron back-scattered diffraction, and transmission electron microscopy were used to quantitatively describe the microstructural evolution through crystallographic analysis, chemical analysis, and volume fraction measurements from the macroscopic scale down to the nanometric scale. During aging, the precipitation of M23C6 carbides, Cr2N nitrides, and σ phase as well as the transformation of ferrite into austenite and austenite into martensite was observed. These complex microstructural changes are controlled by Cr volume diffusion. The precipitation and phase transformation mechanisms are described.

  8. Characterization of a cold-rolled 2101 lean duplex stainless steel.

    PubMed

    Bassani, Paola; Breda, Marco; Brunelli, Katya; Mészáros, Istvan; Passaretti, Francesca; Zanellato, Michela; Calliari, Irene

    2013-08-01

    Duplex stainless steels (DSS) may be defined as a category of steels with a two-phase ferritic-austenitic microstructure, which combines good mechanical and corrosion properties. However, these steels can undergo significant microstructural modification as a consequence of either thermo-mechanical treatments (ferrite decomposition, which causes σ- and χ-phase formation and nitride precipitation) or plastic deformation at room temperature [austenite transformation into strain-induced martensite (SIM)]. These secondary phases noticeably affect the properties of DSS, and therefore are of huge industrial interest. In the present work, SIM formation was investigated in a 2101 lean DSS. The material was subjected to cold rolling at various degrees of deformation (from 10 to 80% thickness reduction) and the microstructure developed after plastic deformation was investigated by electron backscattered diffraction, X-ray diffraction measurements, and hardness and magnetic tests. It was observed that SIM formed as a consequence of deformations higher than ~20% and residual austenite was still observed at 80% of thickness reduction. Furthermore, a direct relationship was found between microstructure and magnetic properties. PMID:23721654

  9. Double-Sided Single-Pass Submerged Arc Welding for 2205 Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Luo, Jian; Yuan, Yi; Wang, Xiaoming; Yao, Zongxiang

    2013-09-01

    The duplex stainless steel (DSS), which combines the characteristics of ferritic steel and austenitic steel, is used widely. The submerged arc welding (SAW) method is usually applied to join thick plates of DSS. However, an effective welding procedure is needed in order to obtain ideal DSS welds with an appropriate proportion of ferrite (δ) and austenite (γ) in the weld zone, particularly in the melted zone and heat-affected zone. This study evaluated the effectiveness of a high efficiency double-sided single-pass (DSSP) SAW joining method for thick DSS plates. The effectiveness of the converse welding procedure, characterizations of weld zone, and mechanical properties of welded joint are analyzed. The results show an increasing appearance and continuous distribution feature of the σ phase in the fusion zone of the leading welded seam. The converse welding procedure promotes the σ phase to precipitate in the fusion zone of leading welded side. The microhardness appears to significantly increase in the center of leading welded side. Ductile fracture mode is observed in the weld zone. A mixture fracture feature appears with a shear lip and tears in the fusion zone near the fusion line. The ductility, plasticity, and microhardness of the joints have a significant relationship with σ phase and heat treatment effect influenced by the converse welding step. An available heat input controlling technology of the DSSP formation method is discussed for SAW of thick DSS plates.

  10. Evolutions of Microstructure and Properties During Cold Rolling of 19Cr Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Ran, Qingxuan; Xu, Wanjian; Wu, Zhaoyu; Li, Jun; Xu, Yulai; Xiao, Xueshan; Hu, Jincheng; Jiang, Laizhu

    2016-10-01

    Evolutions of microstructure, mechanical, and corrosion properties of 19Cr (Fe-18.9Cr-10.1Mn-0.3Ni-0.261N-0.030C-0.5Si) duplex stainless steel have been investigated during cold rolling at room temperature. Dislocation slip dominated deformation mode of ferrite phase. However, deformation mechanism of austenite phase was different with the increasing cold-rolling reductions. Dislocation slip and strengthening effect of twin boundaries caused pile-up phenomenon at the initial deformation stage. When the amount of cold-rolling reduction attained greater than 50 pct, induced α'-martensite appeared in deformed austenite phase. Hardness of austenite phase was higher than that of the deformed ferrite because of its higher strengthening effect during cold-rolling process. Cold-rolling deformation caused deterioration of the pitting corrosion resistance in 3.5 wt pct NaCl aqueous solution. Pitting corrosion always initiated in the ferrite phase and the phase boundary in the solution-treated alloy. Additional pitting holes appeared in deformed austenite phase because of the decrease in corrosion resistance caused by dislocation accumulation and induced α'-martensite.

  11. Characterization of a cold-rolled 2101 lean duplex stainless steel.

    PubMed

    Bassani, Paola; Breda, Marco; Brunelli, Katya; Mészáros, Istvan; Passaretti, Francesca; Zanellato, Michela; Calliari, Irene

    2013-08-01

    Duplex stainless steels (DSS) may be defined as a category of steels with a two-phase ferritic-austenitic microstructure, which combines good mechanical and corrosion properties. However, these steels can undergo significant microstructural modification as a consequence of either thermo-mechanical treatments (ferrite decomposition, which causes σ- and χ-phase formation and nitride precipitation) or plastic deformation at room temperature [austenite transformation into strain-induced martensite (SIM)]. These secondary phases noticeably affect the properties of DSS, and therefore are of huge industrial interest. In the present work, SIM formation was investigated in a 2101 lean DSS. The material was subjected to cold rolling at various degrees of deformation (from 10 to 80% thickness reduction) and the microstructure developed after plastic deformation was investigated by electron backscattered diffraction, X-ray diffraction measurements, and hardness and magnetic tests. It was observed that SIM formed as a consequence of deformations higher than ~20% and residual austenite was still observed at 80% of thickness reduction. Furthermore, a direct relationship was found between microstructure and magnetic properties.

  12. Synchrotron Based Observations of Sigma Phase Formation and Dissolution in Duplex Stainless Steel

    SciTech Connect

    Elmer, J. W.; Palmer, T. A.; Specht, Eliot D

    2007-01-01

    The formation and growth of sigma ({sigma}) phase in 2205 duplex stainless steel was observed and measured in real time using synchrotron radiation during isothermal heat treating at temperatures between 700 C and 850 C. Synchrotron experiments were performed on this material at the Advanced Photon Source (APS) while isothermally holding the samples for times of up to 10 hr. During the isothermal hold, sigma formed in quantities up to 22% as the ferrite transformed to a mixture of sigma and austenite phases. In addition, sigma formed at 850 C was heated to 1000 C to observe its dissolution. The amounts of sigma that formed, and the dissolution temperature of sigma were compared to the results predicted by Thermocalc, showing differences between the calculated and measured values. The synchrotron data was further modeled using a modified Johnson-Mehl-Avrami analysis to determine kinetic parameters for sigma formation. The initial JMA exponent, n, at low fractions of sigma was found to be approximately 7.0, however, towards the end of the transformation, n decreased to values of approximately 0.75. Because of the variable value of n, it was not possible to determine reliable values for the activation energy and pre-exponential terms for the JMA equation. During cooling to room temperature, the high temperature austenite partially transformed to ferrite, substantially increasing the ferrite content while the sigma phase kept its high temperature value.

  13. Influence of nitrogen in the shielding gas on corrosion resistance of duplex stainless steel welds

    NASA Astrophysics Data System (ADS)

    Bhatt, R. B.; Kamat, H. S.; Ghosal, S. K.; de, P. K.

    1999-10-01

    The influence of nitrogen in shielding gas on the corrosion resistance of welds of a duplex stainless steel (grade U-50), obtained by gas tungsten arc (GTA) with filler wire, autogenous GTA (bead-on-plate), electron beam welding (EBW), and microplasma techniques, has been evaluated in chloride solutions at 30 °C. Pitting attack has been observed in GTA, electron beam welding, and microplasma welds when welding has been carried out using pure argon as the shielding gas. Gas tungsten arc welding with 5 to 10% nitrogen and 90 to 95% argon, as the shielding gas, has been found to result in an improved pitting corrosion resistance of the weldments of this steel. However, the resistance to pitting of autogenous welds (bead-on-plate) obtained in pure argon as the shielding gas has been observed to remain unaffected. Microscopic examination, electron probe microanalysis (EPMA), and x-ray diffraction studies have revealed that the presence of nitrogen in the shielding gas in the GTA welds not only modifies the microstructure and the austenite to ferrite ratio but also results in a nearly uniform distribution of the various alloying elements, for example, chromium, nickel, and molybdenum among the constitutent phases, which are responsible for improved resistance to pitting corrosion.

  14. Estimation of fracture toughness of cast stainless steels during thermal aging in LWR systems

    SciTech Connect

    Chopra, O.K. )

    1991-06-01

    A procedure and correlations are presented for predicting the change in fracture toughness of cast stainless steel components due to thermal aging during service in light water rectors (LWRs) at 280--330{degrees}C (535--625{degrees}F). The fracture toughness J-R curve and Charpy-impact energy of aged cast stainless steels are estimated from known mineral in formation. Fracture toughness of a specific cast stainless steel is estimated from the extent and kinetics of thermal embrittlement. The extent of thermal embrittlement is characterized by the room-temperature normalized'' Charpy-impact energy. A correlation for the extent of embrittlement at saturation,'' i.e., the minimum impact energy that would be achieved for the material after long-term aging, is given in terms of a material parameter, {Phi}, which is determined from the chemical composition. The fracture toughness J-R curve for the material is then obtained from correlations between room-temperature Charpy-impact energy and fracture toughness parameters. Fracture toughness as a function of time and temperature of reactor service is estimated from the kinetics of thermal embrittlement, which is determined from chemical composition. A common lower-bound'' J-R curve for cast stainless steels with unknown chemical composition is also defined for a given material specification, ferrite content, and temperature. Examples for estimating impact strength and fracture toughness of cast stainless steel components during reactor service are describes. 24 refs., 39 figs., 2 tabs.

  15. TEM microscopical examination of the magnetic domain boundaries in a super duplex austenitic-ferritic stainless steel

    SciTech Connect

    Fourlaris, G.; Gladman, T.; Maylin, M.

    1996-12-31

    It has been demonstrated in an earlier publication that significant improvements in the coercivity, maximum induction and remanence values can be achieved, by using a 2205 type Duplex austenitic-ferritic stainless steel (DSS) instead of the low alloy medium carbon steels currently being used. These improvements are achieved in the as received 2205 material, and after small amounts of cold rolling have been applied, to increase the strength. In addition, the modification of the duplex austenitic-ferritic microstructure, via a heat treatment route, results in a finer austenite `island` dispersion in a ferritic matrix and provides an attractive option for further modification of the magnetic characteristics of the material. However, the 2205 type DSS exhibits {open_quotes}marginal{close_quotes} corrosion protection in a marine environment, so that a study has been undertaken to examine whether the beneficial effects exhibited by the 2205 DSS, are also present in a 2507 type super-DSS.

  16. The Effect of Constant and Pulsed Current Gas Tungsten Arc Welding on Joint Properties of 2205 Duplex Stainless Steel to 316L Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Neissi, R.; Shamanian, M.; Hajihashemi, M.

    2016-05-01

    In this study, dissimilar 316L austenitic stainless steel/2205 duplex stainless steel (DSS) joints were fabricated by constant and pulsed current gas tungsten arc welding process using ER2209 DSS as a filler metal. Microstructures and joint properties were characterized using optical and electron scanning microscopy, tensile, Charpy V-notch impact and micro-hardness tests, and cyclic polarization measurements. Microstructural observations confirmed the presence of chromium nitride and delta ferrite in the heat-affected zone of DSS and 316L, respectively. In addition, there was some deviation in the austenite/ferrite ratio of the surface welding pass in comparison to the root welding pass. Besides having lower pitting potential, welded joints produced by constant current gas tungsten arc welding process, consisted of some brittle sigma phase precipitates, which resulted in some impact energy reduction. The tensile tests showed high tensile strength for the weld joints in which all the specimens were broken in 316L base metal.

  17. In-Situ Observations of Sigma Phase Dissolution in 2205 Duplex Stainless Steel Using Synchrotron X-Ray Diffraction

    SciTech Connect

    Elmer, J. W.; Palmer, T. A.; Specht, Eliot D

    2007-01-01

    Synchrotron radiation was used to directly observe the transformation of ferrite, austenite and sigma phases during heating and cooling of 2205 duplex stainless steel. Sigma formed during the initial stages of heating, dissolved as the temperature was increased, and reformed on cooling. The dissolution temperature of sigma was measured to be 985 2.8 C at a heating rate of 0.25 C/s, and the kinetics of sigma formation at 850 Cwas determined to be slower after dissolving at 1000 C than before.

  18. In-Situ Observations of Sigma Phase Dissolution in 2205 Duplex Stainless Steel using Synchrotron X-Ray Diffraction

    SciTech Connect

    Elmer, J; Palmer, T; Specht, E

    2006-08-08

    Synchrotron radiation was used to directly observe the transformation of ferrite, austenite and sigma phases during heating and cooling of 2205 duplex stainless steel. Sigma formed during the initial stages of heating, dissolved as the temperature was increased, and reformed on cooling. The dissolution temperature of sigma was measured to be 985 C {+-} 2.8 C at a heating rate of 0.25 C/s, and the kinetics of sigma formation at 850 C was determined to be slower after dissolving at 1000 C than before.

  19. Cast CF8C-Plus Stainless Steel for Turbocharger Applications

    SciTech Connect

    Maziasz, P.J.; Shyam, A.; Evans, N.D.; Pattabiraman, K. (Honeywell Turbo Technologies

    2010-06-30

    The purpose of this Cooperative Research and Development Agreement (CRADA) project is to provide the critical test data needed to qualify CF8C-Plus cast stainless steel for commercial production and use for turbocharger housings with upgraded performance and durability relative to standard commercial cast irons or stainless steels. The turbocharger technologies include, but are not limited to, heavy-duty highway diesel engines, and passenger vehicle diesel and gasoline engines. This CRADA provides additional critical high-temperature mechanical properties testing and data analysis needed to quality the new CF8C-Plus steels for turbocharger housing applications.

  20. Cyclic stress effect on stress corrosion cracking of duplex stainless steel in chloride and caustic solutions

    NASA Astrophysics Data System (ADS)

    Yang, Di

    Duplex stainless steel (DSS) is a dual-phase material with approximately equal volume amount of austenite and ferrite. It has both great mechanical properties (good ductility and high tensile/fatigue strength) and excellent corrosion resistance due to the mixture of the two phases. Cyclic loadings with high stress level and low frequency are experienced by many structures. However, the existing study on corrosion fatigue (CF) study of various metallic materials has mainly concentrated on relatively high frequency range. No systematic study has been done to understand the ultra-low frequency (˜10-5 Hz) cyclic loading effect on stress corrosion cracking (SCC) of DSSs. In this study, the ultra-low frequency cyclic loading effect on SCC of DSS 2205 was studied in acidified sodium chloride and caustic white liquor (WL) solutions. The research work focused on the environmental effect on SCC of DSS 2205, the cyclic stress effect on strain accumulation behavior of DSS 2205, and the combined environmental and cyclic stress effect on the stress corrosion crack initiation of DSS 2205 in the above environments. Potentiodynamic polarization tests were performed to investigate the electrochemical behavior of DSS 2205 in acidic NaCl solution. Series of slow strain rate tests (SSRTs) at different applied potential values were conducted to reveal the optimum applied potential value for SCC to happen. Room temperature static and cyclic creep tests were performed in air to illustrate the strain accumulation effect of cyclic stresses. Test results showed that cyclic loading could enhance strain accumulation in DSS 2205 compared to static loading. Moreover, the strain accumulation behavior of DSS 2205 was found to be controlled by the two phases of DSS 2205 with different crystal structures. The B.C.C. ferrite phase enhanced strain accumulation due to extensive cross-slips of the dislocations, whereas the F.C.C. austenite phase resisted strain accumulation due to cyclic strain

  1. Effects of Cold Rolling and Strain-Induced Martensite Formation in a SAF 2205 Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Breda, Marco; Brunelli, Katya; Grazzi, Francesco; Scherillo, Antonella; Calliari, Irene

    2015-02-01

    Duplex stainless steels (DSSs) are biphasic steels having a ferritic-austenitic microstructure that allows them to combine good mechanical and corrosion-resistance properties. However, these steels are sensitive to microstructural modifications, such as ferrite decomposition at high temperatures and the possibility of strain-induced martensite (SIM) formation from cold-worked austenite, which can significantly alter their interesting features. In the present work, the effects of cold rolling on the developed microstructural features in a cold-rolled SAF 2205 DSS and the onset of martensitic transformation are discussed. The material was deformed at room temperature from 3 to 85 pct thickness reduction, and several characterization techniques (scanning and transmission electron microscopy, X-ray diffraction, hardness measurements, and time-of-flight-neutron diffraction) were employed in order to fully describe the microstructural behavior of the steel. Despite the low stacking fault energy of DSS austenite, which contributed to SIM formation, the steel was found to be more stable than other stainless steel grades, such as AISI 304L. Rolling textures were similar to those pertaining to single-phase materials, but the presence of the biphasic (Duplex) microstructure imposed deformation constraints that affected the developed microstructural features, owing to phases interactions. Moreover, even if an intensification of the strain field in austenite was revealed, retarded SIM transformation kinetics and lower martensite amounts with respect to AISI 304L were observed.

  2. Detection of secondary phases in duplex stainless steel by magnetic force microscopy and scanning Kelvin probe force microscopy

    SciTech Connect

    Ramírez-Salgado, J.; Domínguez-Aguilar, M.A.; Castro-Domínguez, B.; Hernández-Hernández, P.; Newman, R.C.

    2013-12-15

    The secondary phase transformations in a commercial super duplex stainless steel were investigated by micro-chemical analyses and high resolution scanning probe microscopy. Energy dispersive X-ray and electron probe detected ferrite and austenite as well as secondary phases in unetched aged duplex stainless steel type 25Cr-7Ni-3Mo. Volta potential indicated that nitride and sigma appeared more active than ferrite, while secondary austenite and austenite presented a nobler potential. Reversal order in nobility is thought to be attributable to the potential ranking provided by oxide nature diversity as a result of secondary phase surface compositions on steel. After eutectoid transformation, secondary austenite was detected by electron probe microanalysis, whereas atomic force microscopy distinguished this phase from former austenite by image contrast. Magnetic force microscopy revealed a “ghosted” effect on the latter microstructure probably derived from metal memory reminiscence of mechanical polishing at passivity and long range magnetic forces of ferrite phase. - Highlights: • Nobility detection of secondary phases by SKPFM in DSS particles is not a straightforward procedure. • As Volta potential and contrast are not always consistent SKPFM surface oxides is thought played an important role in detection. • AFM distinguished secondary austenite from former austenite by image contrast though SEM required EPMA.

  3. Estimation of fracture toughness of cast stainless steels in LWR (light water reactor) systems

    SciTech Connect

    Chopra, O.K.

    1990-10-01

    A procedure and correlations are presented for predicting fracture toughness J-R curves and impact strength of aged cast stainless steels from known material information. The saturation'' fracture toughness of a specific cast stainless steel, i.e., the minimum fracture toughness that would ever be achieved for the material after long-term service, is estimated from the degree of embrittlement at saturation. Degree of embrittlement is characterized in terms of room-temperature Charpy-impact energy. The variation of the impact energy at saturation for different materials is described in terms of a material parameter {Phi}, which is determined from the chemical composition and ferrite morphology. The fracture toughness J-R curve for the material is then obtained from correlations between room-temperature Charpy-impact energy and fracture toughness. Fracture toughness as a function of time and temperature of reactor service is estimated from the kinetics of embrittlement, which is determined from the chemical composition. Examples for estimating impact strength and fracture toughness of cast stainless steel components during reactor service are described. A common lower-bound'' J-R curve for cast stainless steels with unknown chemical composition is also defined. 15 refs., 19 figs., 3 tabs.

  4. Estimation of mechanical properties of cast stainless steels during thermal aging in LWR systems

    SciTech Connect

    Chopra, O.K.

    1991-10-01

    A procedure and correlations are presented for predicting Charpy- impact energy, tensile flow stress, fracture toughness J-R curve, and J{sub IC} of aged cast stainless steels from known material information. The ``saturation`` impact strength and fracture toughness of a specific cast stainless steel, i.e., the minimum value that would be achieved for the material after long-term service, is estimated from the chemical composition of the steel. Mechanical properties as a function of time and temperature of reactor service are estimated from impact energy and flow stress of the unaged material and the kinetics of embrittlement, which are also determined from chemical composition. The J{sub IC} values are determined from the estimated J-R curve and flow stress. Examples of estimating mechanical properties of cast stainless steel components during reactor service are presented. A common ``lower-bound`` J-R curve for cast stainless steels of unknown chemical composition is also defined for a given grade of steel, ferrite content, and temperature.

  5. Detailed Microstructural Characterization and Restoration Mechanisms of Duplex and Superduplex Stainless Steel Friction-Stir-Welded Joints

    NASA Astrophysics Data System (ADS)

    Santos, T. F. A.; Torres, E. A.; Lippold, J. C.; Ramirez, A. J.

    2016-10-01

    Duplex stainless steels are successfully used in a wide variety of applications in areas such as the food industry, petrochemical installations, and sea water desalination plants, where high corrosion resistance and high mechanical strength are required. However, during fusion welding operations, there can be changes to the favorable microstructure of these materials that compromise their performance. Friction stir welding with a non-consumable pin enables welded joints to be obtained in the solid state, which avoids typical problems associated with solidification of the molten pool, such as segregation of alloying elements and the formation of solidification and liquefaction cracks. In the case of superduplex stainless steels, use of the technique can avoid unbalanced proportions of ferrite and austenite, formation of deleterious second phases, or growth of ferritic grains in the heat-affected zone. Consolidated joints with full penetration were obtained for 6-mm-thick plates of UNS S32101 and S32205 duplex stainless steels, and S32750 and S32760 superduplex steels. The welding heat cycles employed avoided the conditions required for formation of deleterious phases, except in the case of the welded joint of the S32760 steel, where SEM images indicated the formation of secondary phases, as corroborated by decreased mechanical performance. Analysis using EBSD and transmission electron microscopy revealed continuous dynamic recrystallization by the formation of cellular arrays of dislocations in the ferrite and discontinuous dynamic recrystallization in the austenite. Microtexture evaluation indicated the presence of fibers typical of shear in the thermomechanically affected zone. These fibers were not obviously present in the stir zone, probably due to the intensity of microstructural reformulation to which this region was subjected.

  6. X-Ray Photoelectron Spectroscopy Depth Profiling of Electrochemically Prepared Thin Oxide Layers on Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Donik, Črtomir; Kocijan, Aleksandra; Mandrino, Djordje; Jenko, Monika

    2011-10-01

    The surface oxidation of duplex stainless steel (DSS 2205) was studied by X-ray photoelectron spectroscopy (XPS). The experiments were performed on the alloy after controlled oxidation in a chloride-enriched solution at controlled potentials. The evolution of the passive film formed on the DSS in a chloride solution was studied using cyclic voltammetry with XPS surface characterization at selected potentials. The evolution of the oxide films and its specific compositions formed on the DSS was studied as a function of depth. Fe/Cr oxidized layers and oxide thicknesses were observed and correlated with the various potentiostatic potentials. The importance of Mo and Cr inside the oxide films in this article is studied and described, whereas their role in the protective layer, as oxides, is significant.

  7. The influence of composition and microstructure on the HAZ toughness of duplex stainless steels at [minus]20 C

    SciTech Connect

    Lippold, J.C. ); Varol, I.; Baeslack, W.A. III )

    1994-04-01

    The toughness of two commercial duplex stainless steels, Ferralium Alloy 255 and Alloy 2205, was evaluated over a range of cooling rates representative of conditions in the weld heat-affected zone (HAZ). Both alloys exhibited a loss in toughness at the cooling rate extremes, 90 and 2 C/s, resulting from high ferrite content and larger prior ferrite grain size, respectively. Alloy 255 also showed a drop in toughness at an intermediate cooling rate of 50 C/s. This intermediate loss in toughness, not observed in Alloy 2205, results from the interrelationship between austenite and Cr-rich precipitate formation along ferrite grain boundaries. The precipitation mechanisms and their subsequent effect on toughness are described. The practical implications of HAZ microstructure control are also discussed.

  8. Annealing effects on the microstructure and magnetic domain structures of duplex stainless steel studied by in situ technique

    NASA Astrophysics Data System (ADS)

    Guo, L. Q.; Zhao, X. M.; Li, M.; Zhang, W. J.; Bai, Y.; Qiao, L. J.

    2012-10-01

    The effects of annealing temperature on the microstructure and the magnetic domain structures of duplex stainless steel 2507 were investigated by the magnetic force microscopy (MFM), X-ray diffraction (XRD), and electron backscattered diffraction (EBSD). The MFM and XRD results indicated that the volume fraction of ferrite phase increased with increasing annealing temperature, but the lattice constants kept constant. Moreover, with the rise of annealing temperature, the magnetic domain structure in the ferrite phase varied gradually, where the magnetic domain became thinner and the distribution turned more homogeneous. These results gave a direct evidence for the changes of microstructure and magnetic domain structure induced by the annealing treatment. EBSD analysis showed that the orientation of ferrite grains changed after annealing treatments, which coincided with the changes of the microstructure and the magnetic domain structures.

  9. The effect of tungsten and molybdenum additions on the cavitation corrosion behavior of duplex stainless steel (DSS) in seawater

    SciTech Connect

    Al-Hashem, A.; Abdullah, A.; Shalaby, H.M.

    1998-12-31

    Cavitation corrosion studies were conducted on two duplex stainless steel (DSS) specimens of which one was containing tungsten and more molybdenum than the other. Experiments were conducted in seawater using an ultrasonically-induced cavitation facilities. The rate of mass-loss, free corrosion potential, and microscopic examinations were compared for the two alloys in the presence and absence of cavitation. There was negligible mass loss for the two alloys under stagnant conditions. However, some differences were observed between the two alloys with respect to mass-loss, corrosion potential and morphology of attacked areas. The alloy containing tungsten and mover molybdenum experienced more loss in weight regardless of their more noble corrosion potential during cavitation. This difference in behavior was explained in terms of the effect of the alloying elements on the microstructure of the alloys and their susceptibility to absorb the impact energy of cavitation.

  10. Effect of annealing temperature on the pitting corrosion resistance of super duplex stainless steel UNS S32750

    SciTech Connect

    Tan Hua; Jiang Yiming; Deng Bo; Sun Tao; Xu Juliang; Li Jin

    2009-09-15

    The pitting corrosion resistance of commercial super duplex stainless steels SAF2507 (UNS S32750) annealed at seven different temperatures ranging from 1030 deg. C to 1200 deg. C for 2 h has been investigated by means of potentiostatic critical pitting temperature. The microstructural evolution and pit morphologies of the specimens were studied through optical/scanning electron microscope. Increasing annealing temperature from 1030 deg. C to 1080 deg. C elevates the critical pitting temperature, whereas continuing to increase the annealing temperature to 1200 deg. C decreases the critical pitting temperature. The specimens annealed at 1080 deg. C for 2 h exhibit the best pitting corrosion resistance with the highest critical pitting temperature. The pit morphologies show that the pit initiation sites transfer from austenite phase to ferrite phase as the annealing temperature increases. The aforementioned results can be explained by the variation of pitting resistance equivalent number of ferrite and austenite phase as the annealing temperature changes.

  11. Thermally Sprayed Aluminum (TSA) Coatings for Extended Design Life of 22%Cr Duplex Stainless Steel in Marine Environments

    NASA Astrophysics Data System (ADS)

    Paul, S.; Shrestha, S.; Lee, C. M.; Harvey, M. D. F.

    2013-03-01

    In this article, evaluation of sealed and unsealed thermally sprayed aluminum (TSA) for the protection of 22%Cr duplex stainless steel (DSS) from corrosion in aerated, elevated temperature synthetic seawater is presented. The assessments involved general and pitting corrosion tests, external chloride stress corrosion cracking (SCC), and hydrogen-induced stress cracking (HISC). These tests indicated that DSS samples, which would otherwise fail on their own in a few days, did not show pitting or fail under chloride SCC and HISC conditions when coated with TSA (with or without a sealant). TSA-coated specimens failed only at very high stresses (>120% proof stress). In general, TSA offered protection to the underlying or exposed steel by cathodically polarizing it and forming a calcareous deposit in synthetic seawater. The morphology of the calcareous deposit was found to be temperature dependent and in general was of duplex nature. The free corrosion rate of TSA in synthetic seawater was measured to be ~5-8 μm/year at ~18 °C and ~6-7 μm/year at 80 °C.

  12. On the cryogenic magnetic transition and martensitic transformation of the austenite phase of 7MoPLUS duplex stainless steel

    NASA Astrophysics Data System (ADS)

    Lo, K. H.; Lai, J. K. L.

    2010-08-01

    The magnetic behaviour and martensitic transformation at cryogenic temperatures (down to 4 K) of the austenite phase of the duplex stainless steel (DSS), 7MoPLUS, were studied. As regards the prediction of Neel temperature, the empirical expressions for austenitic stainless steels are not applicable to the austenite phase of 7MoPLUS, although the composition of the austenite phase falls within the composition ranges within which the expressions were developed. Regarding the prediction of martensitic point Ms, the applicability of 'old' and recently developed expressions has been examined. The recently developed expressions, which take into account more alloying elements and their interactions, are not suitable for the austenite phase of 7MoPLUS. But for the 'old', simpler expressions, they seem to be valid in the sense that they all predict high stability of the austenite phase. Results obtained from 7MoPLUS were qualitatively the same as those obtained from another DSS, designated as 2205. Reasons for the applicability and inapplicability of these empirical expressions are suggested.

  13. Heat treatment giving a stable high temperature micro-structure in cast austenitic stainless steel

    DOEpatents

    Anton, Donald L.; Lemkey, Franklin D.

    1988-01-01

    A novel micro-structure developed in a cast austenitic stainless steel alloy and a heat treatment thereof are disclosed. The alloy is based on a multicomponent Fe-Cr-Mn-Mo-Si-Nb-C system consisting of an austenitic iron solid solution (.gamma.) matrix reinforced by finely dispersed carbide phases and a heat treatment to produce the micro-structure. The heat treatment includes a prebraze heat treatment followed by a three stage braze cycle heat treatment.

  14. High-Temperature Performance of Cast CF8C-Plus Austenitic Stainless Steel

    SciTech Connect

    Maziasz, Philip J; Pint, Bruce A

    2011-01-01

    Covers and casings of small to medium size gas turbines can be made from cast austenitic stainless steels, including grades such as CF8C, CF3M, or CF10M. Oak Ridge National Laboratory and Caterpillar have developed a new cast austenitic stainless steel, CF8C-Plus, which is a fully austenitic stainless steel, based on additions of Mn and N to the standard Nb-stabilized CF8C steel grade. The Mn addition improves castability, as well as increases the alloy solubility for N, and both Mn and N synergistically act to boost mechanical properties. CF8C-Plus steel has outstanding creep-resistance at 600-900 C, which compares well with Ni-based superalloys such as alloys X, 625, 617, and 230. CF8C-Plus also has very good fatigue and thermal fatigue resistance. It is used in the as-cast condition, with no additional heat-treatments. While commercial success for CF8C-Plus has been mainly for diesel exhaust components, this steel can also be considered for gas turbine and microturbine casings. The purposes of this paper are to demonstrate some of the mechanical properties, to update the long-term creep-rupture data, and to present new data on the high-temperature oxidation behavior of these materials, particularly in the presence of water vapor.

  15. 77 K Fatigue Crack Growth Rate of Modified CF8M Stainless Steel Castings

    SciTech Connect

    Walsh, R. P.; Toplosky, V. J.; Han, K.; Heitzenroeder, P. J.; Nelson, B. E.

    2006-03-31

    The National Compact Stellerator Experiment (NCSX) is the first of a new class of stellarators. The modular superconducting coils in the NCSX have complex geometry that are manufactured on cast stainless steel (modified CF8M) winding forms. Although CF8M castings have been used before at cryogenic temperature there is limited data available for their mechanical properties at low temperatures. The fatigue life behavior of the cast material is vital thus a test program to generate data on representative material has been conducted. Fatigue test specimens have been obtained from key locations within prototype winding forms to determine the 77 K fatigue crack growth rate. The testing has successfully developed a representative database that ensures confident design. The measured crack growth rates are analyzed in terms of the Paris law parameters and the crack growth properties are related to the materials microstructure.

  16. NDE evaluation of the intergranular corrosion susceptibility of a 2205 duplex stainless steel using thermoelectric power and double loop electrochemical potentiokinetic reactivation methods

    NASA Astrophysics Data System (ADS)

    Ortiz, N.; Carreón, H.; Ruiz, A.

    2013-01-01

    There is a need for a nondestructive technique to assess rapidly and with confidence the degree of sensitization (DOS) in duplex stainless steel (DSS). In this investigation, we present the use of thermoelectric power (TEP) measurements as nondestructive method for the determination of DOS in isothermally aged 2205 DSS at 700°C for different aging times. The DOS of the aged samples was first established by performing the double loop electrochemical potentiokinetic reactivation (DL-EPR) test. The microstructural evolution was evaluated by scanning electron microscopy (SEM). Experimental results indicate that TEP coefficient is sensitive to gradual microstructural changes produced by thermal aging and can be used to monitor IGC sensitization of 2205 duplex stainless steel.

  17. A process model for the heat-affected zone microstructure evolution in duplex stainless steel weldments: Part II. Application to electron beam welding

    NASA Astrophysics Data System (ADS)

    Hemmer, H.; Grong, Ø.; Klokkehaug, S.

    2000-03-01

    In the present investigation, a process model for electron beam (EB) welding of different grades of duplex stainless steels (i.e. SAF 2205 and 2507) has been developed. A number of attractive features are built into the original finite element code, including (1) a separate module for prediction of the penetration depth and distribution of the heat source into the plate, (2) adaptive refinement of the three-dimensional (3-D) element mesh for quick and reliable solution of the differential heat flow equation, and (3) special subroutines for calculation of the heat-affected zone (HAZ) microstructure evolution. The process model has been validated by comparison with experimental data obtained from in situ thermocouple measurements and optical microscope examinations. Subsequently, its aptness to alloy design and optimization of welding conditions for duplex stainless steels is illustrated in different numerical examples and case studies pertaining to EB welding of tubular joints.

  18. Mechanical properties of thermally aged cast stainless steels from shippingport reactor components.

    SciTech Connect

    Chopra, O. K.; Shack, W. J.; Energy Technology

    1995-06-07

    Thermal embrittlement of static-cast CF-8 stainless steel components from the decommissioned Shippingport reactor has been characterized. Cast stainless steel materials were obtained from four cold-leg check valves, three hot-leg main shutoff valves, and two pump volutes. The actual time-at-temperature for the materials was {approx}13 y at {approx}281 C (538 F) for the hot-leg components and {approx}264 C (507 F) for the cold-leg components. Baseline mechanical properties for as-cast material were determined from tests on either recovery-annealed material, i.e., annealed for 1 h at 550 C and then water quenched, or material from the cooler region of the component. The Shippingport materials show modest decreases in fracture toughness and Charpy-impact properties and a small increase in tensile strength because of relatively low service temperatures and ferrite content of the steel. The procedure and correlations developed at Argonne National Laboratory for estimating mechanical properties of cast stainless steels predict accurate or slightly lower values for Charpy-impact energy, tensile flow stress, fracture toughness J-R curve, and JIC of the materials. The kinetics of thermal embrittlement and degree of embrittlement at saturation, i.e., the minimum impact energy achieved after long-term aging, were established from materials that were aged further in the laboratory. The results were consistent with the estimates. The correlations successfully predicted the mechanical properties of the Ringhals 2 reactor hot- and crossover-leg elbows (CF-8M steel) after service of {approx}15 y and the KRB reactor pump cover plate (CF-8) after {approx}8 y of service.

  19. Mechanical properties of thermally aged cast stainless steels from Shippingport reactor components

    SciTech Connect

    Chopra, O.K.; Shack, W.J.

    1995-04-01

    Thermal embrittlement of static-cast CF-8 stainless steel components from the decommissioned Shippingport reactor has been characterized. Cast stainless steel materials were obtained from four cold-leg check valves, three hot-leg main shutoff valves, and two pump volutes. The actual time-at-temperature for the materials was {approximately}13 y at {approximately}281 C (538 F) for the hot-leg components and {approximately}264 C (507 F) for the cold-leg components. Baseline mechanical properties for as-cast material were determined from tests on either recovery-annealed material, i.e., annealed for 1 h at 550 C and then water quenched, or material from the cooler region of the component. The Shippingport materials show modest decreases in fracture toughness and Charpy-impact properties and a small increase in tensile strength because of relatively low service temperatures and ferrite content of the steel. The procedure and correlations developed at Argonne National Laboratory for estimating mechanical properties of cast stainless steels predict accurate or slightly lower values for Charpy-impact energy, tensile flow stress, fracture toughness J-R curve, and J{sub IC} of the materials. The kinetics of thermal embrittlement and degree of embrittlement at saturation, i.e., the minimum impact energy achieved after long-term aging, were established from materials that were aged further in the laboratory. The results were consistent with the estimates. The correlations successfully predicted the mechanical properties of the Ringhals 2 reactor hot and crossover-leg elbows (CF-8M steel) after service of {approximately} 15 y and the KRB reactor pump cover plate (CF-8) after {approximately} 8 y of service.

  20. The effect of chloride ions on the corroded surface layer of 00Cr22Ni5Mo3N duplex stainless steel under cavitation.

    PubMed

    Wan, Tong; Xiao, Ning; Shen, Hanjie; Yong, Xingyue

    2016-11-01

    The effects of Cl(-) on the corroded surface layer of 00Cr22Ni5Mo3N duplex stainless steel under cavitation in chloride solutions were investigated using nanoindentation in conjunction with XRD and XPS. The results demonstrate that Cl(-) had a strong effect on the nano-mechanical properties of the corroded surface layer under cavitation, and there was a threshold Cl(-) concentration. Furthermore, a close relationship between the nano-mechanical properties and the cavitation corrosion resistance of 00Cr22Ni5Mo3N duplex stainless steel was observed. The degradation of the nano-mechanical properties of the corroded surface layer was accelerated by the synergistic effect between cavitation erosion and corrosion. A key factor was the adsorption of Cl(-), which caused a preferential dissolution of the ferrous oxides in the passive film layer on the corroded surface layer. Cavitation further promoted the preferential dissolution of the ferrous oxides in the passive film layer. Simultaneously, cavitation accelerated the erosion of the ferrite in the corroded surface layer, resulting in the degradation of the nano-mechanical properties of the corroded surface layer on 00Cr22Ni5Mo3N duplex stainless steel under cavitation. PMID:27245950

  1. Estimation of fracture toughness of cast stainless steels during thermal aging in LWR systems-revision 1

    SciTech Connect

    Chopra, O.K

    1994-08-01

    This report presents a revision of the procedure and correlations presented earlier in NUREG/CR-4513, ANL-90/42 (June 1991) for predicting the change in mechanical properties of cast stainless steel components due to thermal aging during service in light water reactors at 280-330{degrees}C (535-625{degrees}F). The correlations presented in this report are based on an expanded data base and have been optimized with mechanical-property data on cast stainless steels aged up to {approx}58,000 h at 290-350{degrees}C (554-633{degrees}F). The fracture toughness J-R curve, tensile stress, and Charpy-impact energy of aged cast stainless steels are estimated from known material information. Mechanical properties of a specific cast stainless steel are estimated from the extent and kinetics of thermal embrittlement. Embrittlement of cast stainless steels is characterized in terms of room-temperature Charpy-impact energy. Charpy-impact energy as a function of time and temperature of reactor service is estimated from the kinetics of thermal embrittlement, which are also determined from the chemical composition. The initial impact energy of the unaged steel is required for these estimations. Initial tensile flow stress is needed for estimating the flow stress of the aged material. The fracture toughness J-R curve for the material is then obtained by correlating room-temperature Charpy-impact energy with fracture toughness parameters. The values of J{sub IC} are determined from the estimated J-R curve and flow stress. A common {open_quotes}predicted lower-bound{close_quotes} J-R curve for cast stainless steels of unknown chemical composition is also defined for a given grade of steel, range of ferrite content, and temperature. Examples of estimating mechanical properties of cast stainless steel components during reactor service are presented.

  2. Investigation on the Behavior of Austenite and Ferrite Phases at Stagnation Region in the Turning of Duplex Stainless Steel Alloys

    NASA Astrophysics Data System (ADS)

    Nomani, J.; Pramanik, A.; Hilditch, T.; Littlefair, G.

    2016-06-01

    This paper investigates the deformation mechanisms and plastic behavior of austenite and ferrite phases in duplex stainless steel alloys 2205 and 2507 under chip formation from a machine turning operation. SEM images and EBSD phase mapping of frozen chip root samples detected a build-up of ferrite bands in the stagnation region, and between 65 and 85 pct, more ferrite was identified in the stagnation region compared to austenite. SEM images detected micro-cracks developing in the ferrite phase, indicating ferritic build-up in the stagnation region as a potential triggering mechanism to the formation of built-up edge, as transgranular micro-cracks found in the stagnation region are similar to micro-cracks initiating built-up edge formation. Higher plasticity of austenite due to softening under high strain is seen responsible for the ferrite build-up. Flow lines indicate that austenite is plastically deforming at a greater rate into the chip, while ferrite shows to partition most of the strain during deformation. The loss of annealing twins and activation of multiple slip planes triggered at high strain may explain the highly plastic behavior shown by austenite.

  3. Direct Observations of Sigma Phase Formation in Duplex Stainless Steels Using In Situ Synchrotron X-Ray Diffraction

    SciTech Connect

    Elmer, J. W.; Palmer, T. A.; Specht, Eliot D

    2007-01-01

    The formation and growth of sigma ( ) phase in 2205 duplex stainless steel (DSS) was observed and measured in real time using synchrotron radiation during 10 hour isothermal heat treatments at temperatures between 700 C and 850 C. Sigma formed in near-equilibrium quantities during the isothermal holds, starting from a microstructure which contained a balanced mixture of metastable ferrite and austenite. In-situ synchrotron diffraction continuously monitored the transformation, and these results were compared to those predicted by thermodynamic calculations. The data were further analyzed using a modified Johnson-Mehl-Avrami-Kolmogrov (JMAK) approach to determine kinetic parameters for sigma formation over this temperature range. The initial JMAK exponent, n, at low fractions of sigma was found to be approximately 7.0; however, toward the end of the transformation, n decreased to values of approximately 0.75. The change in the JMAK exponent was attributed to a change in the transformation mechanism from discontinuous precipitation with increasing nucleation rate, to growth of the existing sigma phase after nucleation site saturation occurred. Because of this change in mechanism, it was not possible to determine reliable values for the activation energy and pre-exponential terms for the JMAK equation. While cooling back to room temperature, the partial transformation of austenite resulted in a substantial increase in the ferrite content, but sigma retained its high-temperature value to room temperature.

  4. Direct Observations of Sigma Phase Formation in Duplex Stainless Steels using In Situ Synchrotron X-Ray Diffraction

    SciTech Connect

    Elmer, J W; Palmer, T A; Specht, E D

    2006-07-03

    The formation and growth of sigma phase in 2205 duplex stainless steel was observed and measured in real time using synchrotron radiation during 10 hr isothermal heat treatments at temperatures between 700 C and 850 C. Sigma formed in near-equilibrium quantities during the isothermal holds, starting from a microstructure which contained a balanced mixture of metastable ferrite and austenite. In situ synchrotron diffraction continuously monitored the transformation, and these results were compared to those predicted by thermodynamic calculations. Differences between the calculated and measured amounts of sigma, ferrite and austenite suggest that the thermodynamic calculations underpredict the sigma dissolution temperature by approximately 50 C. The data were further analyzed using a modified Johnson-Mehl-Avrami (JMA) approach to determine kinetic parameters for sigma formation over this temperature range. The initial JMA exponent, n, at low fractions of sigma was found to be approximately 7.0, however, towards the end of the transformation, n decreased to values of approximately 0.75. The change in the JMA exponent was attributed to a change in the transformation mechanism from discontinuous precipitation with increasing nucleation rate, to growth of the existing sigma phase after nucleation site saturation occurred. Because of this change in mechanism, it was not possible to determine reliable values for the activation energy and pre-exponential terms for the JMA equation. While cooling back to room temperature, the partial transformation of austenite resulted in a substantial increase in the ferrite content, but sigma retained its high temperature value to room temperature.

  5. Characterization of Low Temperature Ferrite/Austenite Transformations in the Heat Affected Zone of 2205 Duplex Stainless Steel Arc Welds

    SciTech Connect

    Palmer, T A; Elmer, J W; Babu, S S; Vitek, J M

    2003-08-20

    Spatially Resolved X-Ray Diffraction (SRXRD) has been used to identify a previously unobserved low temperature ferrite ({delta})/austenite({gamma}) phase transformation in the heat affected zone (HAZ) of 2205 Duplex Stainless Steel (DSS) welds. In this ''ferrite dip'' transformation, the ferrite transforms to austenite during heating to peak temperatures on the order of 750 C, and re-transforms to ferrite during cooling, resulting in a ferrite volume fraction equivalent to that in the base metal. Time Resolved X-Ray Diffraction (TRXRD) and laser dilatometry measurements during Gleeble{reg_sign} thermal simulations are performed in order to verify the existence of this low temperature phase transformation. Thermodynamic and kinetic models for phase transformations, including both local-equilibrium and para-equilibrium diffusion controlled growth, show that diffusion of substitutional alloying elements does not provide a reasonable explanation for the experimental observations. On the other hand, the diffusion of interstitial alloying elements may be rapid enough to explain this behavior. Based on both the experimental and modeling results, two mechanisms for the ''ferrite dip'' transformation, including the formation and decomposition of secondary austenite and an athermal martensitic-type transformation of ferrite to austenite, are considered.

  6. Metallurgical and Corrosion Characterization of POST Weld Heat Treated Duplex Stainless Steel (uns S31803) Joints by Friction Welding Process

    NASA Astrophysics Data System (ADS)

    Asif M., Mohammed; Shrikrishna, Kulkarni Anup; Sathiya, P.

    2016-02-01

    The present study focuses on the metallurgical and corrosion characterization of post weld heat treated duplex stainless steel joints. After friction welding, it was confirmed that there is an increase in ferrite content at weld interface due to dynamic recrystallization. This caused the weldments prone to pitting corrosion attack. Hence the post weld heat treatments were performed at three temperatures 1080∘C, 1150∘C and 1200∘C with 15min of aging time. This was followed by water and oil quenching. The volume fraction of ferrite to austenite ratio was balanced and highest pit nucleation resistance were achieved after PWHT at 1080∘C followed by water quench and at 1150∘C followed by oil quench. This had happened exactly at parameter set containing heating pressure (HP):40 heating time (HT):4 upsetting pressure (UP):80 upsetting time (UP):2 (experiment no. 5). Dual phase presence and absence of precipitates were conformed through TEM which follow Kurdjumov-Sachs relationship. PREN of ferrite was decreasing with increase in temperature and that of austenite increased. The equilibrium temperature for water quenching was around 1100∘C and that for oil quenching was around 1140∘C. The pit depths were found to be in the range of 100nm and width of 1.5-2μm.

  7. Real Time Imaging of Deuterium in a Duplex Stainless Steel Microstructure by Time-of-Flight SIMS

    NASA Astrophysics Data System (ADS)

    Sobol, O.; Straub, F.; Wirth, Th.; Holzlechner, G.; Boellinghaus, Th.; Unger, W. E. S.

    2016-02-01

    For more than one century, hydrogen assisted degradation of metallic microstructures has been identified as origin for severe technical component failures but the mechanisms behind have not yet been completely understood so far. Any in-situ observation of hydrogen transport phenomena in microstructures will provide more details for further elucidation of these degradation mechanisms. A novel experiment is presented which is designed to elucidate the permeation behaviour of deuterium in a microstructure of duplex stainless steel (DSS). A hydrogen permeation cell within a TOF-SIMS instrument enables electrochemical charging with deuterium through the inner surface of the cell made from DSS. The outer surface of the DSS permeation cell exposed to the vacuum has been imaged by TOF-SIMS vs. increasing time of charging with subsequent chemometric treatment of image data. This in-situ experiment showed evidently that deuterium is permeating much faster through the ferrite phase than through the austenite phase. Moreover, a direct proof for deuterium enrichment at the austenite-ferrite interface has been found.

  8. Real Time Imaging of Deuterium in a Duplex Stainless Steel Microstructure by Time-of-Flight SIMS

    PubMed Central

    Sobol, O.; Straub, F.; Wirth, Th.; Holzlechner, G.; Boellinghaus, Th.; Unger, W. E. S.

    2016-01-01

    For more than one century, hydrogen assisted degradation of metallic microstructures has been identified as origin for severe technical component failures but the mechanisms behind have not yet been completely understood so far. Any in-situ observation of hydrogen transport phenomena in microstructures will provide more details for further elucidation of these degradation mechanisms. A novel experiment is presented which is designed to elucidate the permeation behaviour of deuterium in a microstructure of duplex stainless steel (DSS). A hydrogen permeation cell within a TOF-SIMS instrument enables electrochemical charging with deuterium through the inner surface of the cell made from DSS. The outer surface of the DSS permeation cell exposed to the vacuum has been imaged by TOF-SIMS vs. increasing time of charging with subsequent chemometric treatment of image data. This in-situ experiment showed evidently that deuterium is permeating much faster through the ferrite phase than through the austenite phase. Moreover, a direct proof for deuterium enrichment at the austenite-ferrite interface has been found. PMID:26832311

  9. Physical Simulation of a Duplex Stainless Steel Friction Stir Welding by the Numerical and Experimental Analysis of Hot Torsion Tests

    NASA Astrophysics Data System (ADS)

    da Fonseca, Eduardo Bertoni; Santos, Tiago Felipe Abreu; Button, Sergio Tonini; Ramirez, Antonio Jose

    2016-09-01

    Physical simulation of friction stir welding (FSW) by means of hot torsion tests was performed on UNS S32205 duplex stainless steel. A thermomechanical simulator Gleeble 3800® with a custom-built liquid nitrogen cooling system was employed to reproduce the thermal cycle measured during FSW and carry out the torsion tests. Microstructures were compared by means of light optical microscopy and electron backscatter diffraction. True strain and strain rate were calculated by numerical simulation of the torsion tests. Thermomechanically affected zone (TMAZ) was reproduced at peak temperature of 1303 K (1030 °C), rotational speeds of 52.4 rad s-1 (500 rpm) and 74.5 rad s-1 (750 rpm), and 0.5 to 0.75 revolutions, which represent strain rate between 10 and 16 s-1 and true strain between 0.5 and 0.8. Strong grain refinement, similar to the one observed in the stir zone (SZ), was attained at peak temperature of 1403 K (1130 °C), rotational speed of 74.5 rad s-1 (750 rpm), and 1.2 revolution, which represent strain rate of 19 s-1 and true strain of 1.3. Continuous dynamic recrystallization in ferrite and dynamic recrystallization in austenite were observed in the TMAZ simulation. At higher temperature, dynamic recovery of austenite was also observed.

  10. Effect of Austenitic and Austeno-Ferritic Electrodes on 2205 Duplex and 316L Austenitic Stainless Steel Dissimilar Welds

    NASA Astrophysics Data System (ADS)

    Verma, Jagesvar; Taiwade, Ravindra V.

    2016-09-01

    This study addresses the effect of different types of austenitic and austeno-ferritic electrodes (E309L, E309LMo and E2209) on the relationship between weldability, microstructure, mechanical properties and corrosion resistance of shielded metal arc welded duplex/austenitic (2205/316L) stainless steel dissimilar joints using the combined techniques of optical, scanning electron microscope, energy-dispersive spectrometer and electrochemical. The results indicated that the change in electrode composition led to microstructural variations in the welds with the development of different complex phases such as vermicular ferrite, lathy ferrite, widmanstatten and intragranular austenite. Mechanical properties of welded joints were diverged based on compositions and solidification modes; it was observed that ferritic mode solidified weld dominated property wise. However, the pitting corrosion resistance of all welds showed different behavior in chloride solution; moreover, weld with E2209 was superior, whereas E309L exhibited lower resistance. Higher degree of sensitization was observed in E2209 weld, while lesser in E309L weld. Optimum ferrite content was achieved in all welds.

  11. Assessment of Crack Detection in Heavy-Walled Cast Stainless Steel Piping Welds Using Advanced Low-Frequency Ultrasonic Methods

    SciTech Connect

    Anderson, Michael T.; Crawford, Susan L.; Cumblidge, Stephen E.; Denslow, Kayte M.; Diaz, Aaron A.; Doctor, Steven R.

    2007-03-01

    Studies conducted at the Pacific Northwest National Laboratory in Richland, Washington, have focused on assessing the effectiveness and reliability of novel approaches to nondestructive examination (NDE) for inspecting coarse-grained, cast stainless steel reactor components. The primary objective of this work is to provide information to the U.S. Nuclear Regulatory Commission on the effectiveness and reliability of advanced NDE methods as related to the inservice inspection of safety-related components in pressurized water reactors (PWRs). This report provides progress, recent developments, and results from an assessment of low frequency ultrasonic testing (UT) for detection of inside surface-breaking cracks in cast stainless steel reactor piping weldments as applied from the outside surface of the components. Vintage centrifugally cast stainless steel piping segments were examined to assess the capability of low-frequency UT to adequately penetrate challenging microstructures and determine acoustic propagation limitations or conditions that may interfere with reliable flaw detection. In addition, welded specimens containing mechanical and thermal fatigue cracks were examined. The specimens were fabricated using vintage centrifugally cast and statically cast stainless steel materials, which are typical of configurations installed in PWR primary coolant circuits. Ultrasonic studies on the vintage centrifugally cast stainless steel piping segments were conducted with a 400-kHz synthetic aperture focusing technique and phased array technology applied at 500 kHz, 750 kHz, and 1.0 MHz. Flaw detection and characterization on the welded specimens was performed with the phased array method operating at the frequencies stated above. This report documents the methodologies used and provides results from laboratory studies to assess baseline material noise, crack detection, and length-sizing capability for low-frequency UT in cast stainless steel piping.

  12. Ultrasonic Sound Field Mapping Through Coarse Grained Cast Austenitic Stainless Steel Components

    SciTech Connect

    Crawford, Susan L.; Prowant, Matthew S.; Cinson, Anthony D.; Larche, Michael R.; Diaz, Aaron A.

    2014-08-01

    The Pacific Northwest National Laboratory (PNNL) has been involved with nondestructive examination (NDE) of coarse-grained cast austenitic stainless steel (CASS) components for over 30 years. More recent work has focused on mapping the ultrasonic sound fields generated by low-frequency phased array probes that are typically used for the evaluation of CASS materials for flaw detection and characterization. The casting process results in the formation of large grained material microstructures that are nonhomogeneous and anisotropic. The propagation of ultrasonic energy for examination of these materials results in scattering, partitioning and redirection of these sound fields. The work reported here provides an assessment of sound field formation in these materials and provides recommendations on ultrasonic inspection parameters for flaw detection in CASS components.

  13. Long-term aging of cast stainless steels: Mechanisms and resulting properties

    SciTech Connect

    Chopra, O.K.; Chung, H.M.

    1987-09-01

    Mechanical property data are presented from Charpy-impact, tensile, and J-R curve tests for several heats of cast stainless steel aged up to 10,000 h at 450, 400, 350, 320, and 290/sup 0/C. The results indicate that thermal aging increases the tensile strength and decreases the impactenergy, J/sub IC/ and tearing modulus of the steels. Also, the ductile-to-brittle transition curve shifts to higher temperatures. The low-carbon CF-3 steels were the most resistant and the molybdenum-containing high-carbon CF-8M steels were the most susceptible to low-temperature embrittlement. The influence of nitrogen content and distribution of ferrite on loss of toughness are discussed. Data also indicate that existing correlations do not accurately represent the embrittlement behavior over the temperature range 280 to 450/sup 0/C, i.e., extrapolation of high-temperature data to reactor temperatures may not be valid for some compositions of cast stainless steels. 13 refs., 13 figs., 2 tabs.

  14. Elastic-plastic characterization of a cast stainless steep pipe elbow material

    SciTech Connect

    Joyce, J.A.; Hackett, E.M.; Roe, C.

    1992-01-01

    Tests conducted in Japan as part of the High Level Vibration Test (HLVT) program for reactor piping systems revealed fatigue crack growth in a cast stainless steel pipe elbow. The material tested was equivalent to ASME SA-351CF8M. The David Taylor Research Center (DTRC) was tasked to developed the appropriate material property data to characterize cyclic deformation, cyclic elastic-plastic crack growth and ductile tearing resistance in the pipe elbow material. It was found that the cast stainless steel was very resistant to ductile crack extension. J-R curves essentially followed a blunting behavior to very high J levels. Low cycle fatigue crack growth rate data obtained on this material using a cyclic J integral approach was consistent with the high cycle fatigue crack growth rate and with a standard textbook correlation equation typical for this type of material. Evaluation of crack closure effects was essential to accurately determine the crack driving force for cyclic elastic- plastic crack growth in this material. SEM examination of several of the cyclic J test fracture surfaces indicated that fatigue was the primary mode of fracture with ductile crack extension intervening only during the last few cycles of loading.

  15. Influence of volumic heat treatments upon cavitation erosion resistance of duplex X2CrNiMoN 22-5-3 stainless steels

    NASA Astrophysics Data System (ADS)

    Micu, L. M.; Bordeasu, I.; Popoviciu, M. O.; Popescu, M.; Bordeaşu, D.; Salcianu, L. C.

    2015-06-01

    The stainless steels Duplex 2205 with austenite and ferrite structure have mechanical characteristics close to those of martensite stainless steels but a better corrosion resistance; these steels are very sensitive on the heat treatments. Present work studies the cavitation erosion for those steels for three different heat treatments: simply quenched, annealed at 475°C post quenching and annealed at 875°C. The researches were undertaken at Timisoara “Politehnica” University in the Laboratory of Material Science and the Laboratory of Cavitation, using the T2 facility which integrally respects the recommendation of ASTM G32- 10 Standard. The best results were obtained with the specimens annealed at 875°C. In comparison with the stainless steel 41Cr4, with very good cavitation erosion qualities, all tested steels presented also good erosion resistance. So, Duplex 2205 steels can be used for details subjected to cavitation. The best results are obtained by increasing both the hardness and the quantity of the structure constituent with better cavitation erosion resistance, in our case the alloyed austenite.

  16. Decomposition Kinetics of Ferrite in Isothermally Aged SAF 2507-Type Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Berecz, Tibor; Fazakas, Éva; Mészáros, István; Sajó, István

    2015-12-01

    Decomposition of the ferritic phase is studied in isothermally aged SAF 2507 superduplex stainless steel (SDSS) by means of different examination methods. The ferritic phase ( δ) undergoes an eutectoid transformation into secondary austenite ( γ 2) and σ-phase between 650 and 1000 °C. Samples were treated at 900 °C because the incubation time of this transformation is the shortest at this temperature. In order to follow the microstructural changes, x-ray diffraction analysis (XRD), automated electron backscatter diffraction (EBSD), applied magnetic investigation [vibrating sample magnetometer (VSM)], micro-hardness tests, and differential thermal analysis (DTA) were used. The results of XRD and EBSD methods for phase quantification showed nearly the same amounts for all three phases. The results of applied magnetic investigation for the fraction of ferritic phase were also in good agreement with the corresponding results of XRD and EBSD methods. Decomposition of ferrite is similarly well-traceable on EBSD phase maps where the coherent ferritic areas gradually broke into pieces with increasing time of heat treatment. According to the EBSD measurements the σ-phase grains appeared and started to grow after 2 min aging time in the ferritic-austenitic matrix, usually on the boundaries of ferritic and austenitic grains. After 15 min treating time, the microstructure consisted of mainly σ- and austenitic (primary and secondary) phases with negligible amount of ferrite. Chemical composition of the σ-phase was measured by energy-dispersive x-ray spectroscopy (EDS) at different aging times. Activation energies of σ-phase precipitation and α'-phase formation were determined by the Kissinger plot, through DTA measurements; they are 243 and 261 kJ/mol, respectively. Using the results of phase quantifications, the Johnson-Mehl-Avrami equation was fitted.

  17. Alloy Shrinkage factors for the investment casting of 17-4PH stainless steel parts

    SciTech Connect

    Sabau, Adrian S; Porter, Wallace D

    2008-01-01

    In this study, the alloy shrinkage factors were obtained for the investment casting of 17-4PH stainless steel parts. For the investment casting process, unfilled wax and fused silica with a zircon prime coat were used for patterns and shell molds, respectively. Dimensions of the die tooling, wax pattern, and casting were measured using a Coordinate Measurement Machine. For all the properties, the experimental data available in the literature did not cover the entire temperature range necessary for process simulation. A comparison between the predicted material property data measured property data is made. It was found that most material properties were accurately predicted over the most of the temperature range of the process. Several assumptions were made in order to obtain a complete set of mechanical property data at high temperatures. Thermal expansion measurements for the 17-4PH alloy were conducted at heating and cooling. As a function of temperature, the thermal expansion for both the alloy and shell mold materials showed different evolution at heating and cooling. Thus, one generic simulation were performed with thermal expansion obtained at heating and another one with thermal expansion obtained at cooling. The alloy dimensions were obtained from numerical simulation results of solidification, heat transfer, and deformation phenomena. As compared with experimental results, the numerical simulation results for the shrinkage factors were slightly over-predicted.

  18. Engineering study for a melting, casting, rolling and fabrication facility for recycled contaminated stainless steel

    SciTech Connect

    1994-01-01

    This Preliminary Report is prepared to study the facilities required for recycling contaminated stainless steel scrap into plate which will be fabricated into boxes suitable for the storage of contaminated wastes and rubble. The study is based upon the underlying premise that the most cost effective way to produce stainless steel is to use the same processes employed by companies now in production of high quality stainless steel. Therefore, the method selected for this study for the production of stainless steel plate from scrap is conventional process using an Electric Arc Furnace for meltdown to hot metal, a Continuous Caster for production of cast slabs, and a Reversing Hot Mill for rolling the slabs into plate. The fabrication of boxes from the plate utilizes standard Shears, Punch Presses and welding equipment with Robotic Manipulators. This Study presumes that all process fumes, building dusts and vapors will be cycled through a baghouse and a nuclear grade HEPA filter facility prior to discharge. Also, all process waste water will be evaporated into the hot flue gas stream from the furnace utilizing a quench tank; so there will be no liquid discharges from the facility and all vapors will be processed through a HEPA filter. Even though HEPA filters are used today in controlling radioactive contamination from nuclear facilities there is a sparsity of data concerning radioactivity levels and composition of waste that may be collected from contaminated scrap steel processing. This report suggests some solutions to these problems but it is recommended that additional study must be given to these environmental problems.

  19. Electron work functions of ferrite and austenite phases in a duplex stainless steel and their adhesive forces with AFM silicon probe

    PubMed Central

    Guo, Liqiu; Hua, Guomin; Yang, Binjie; Lu, Hao; Qiao, Lijie; Yan, Xianguo; Li, Dongyang

    2016-01-01

    Local electron work function, adhesive force, modulus and deformation of ferrite and austenite phases in a duplex stainless steel were analyzed by scanning force microscopy. It is demonstrated that the austenite has a higher electron work function than the ferrite, corresponding to higher modulus, smaller deformation and larger adhesive force. Relevant first-principles calculations were conducted to elucidate the mechanism behind. It is demonstrated that the difference in the properties between austenite and ferrite is intrinsically related to their electron work functions. PMID:26868719

  20. A study on the mechanism of stress corrosion cracking of duplex stainless steels in hot alkaline-sulfide solution

    NASA Astrophysics Data System (ADS)

    Chasse, Kevin Robert

    Duplex stainless steels (DSS) generally have superior strength and corrosion resistance as compared to most standard austenitic and ferritic stainless grades owing to a balanced microstructure of austenite and ferrite. As a result of having favorable properties, DSS have been selected for the construction of equipment in pulp and paper, chemical processing, nuclear, oil and gas as well as other industries. The use of DSS has been restricted in some cases because of stress corrosion cracking (SCC), which can initiate and grow in either the ferrite or austenite phase depending on the environment. Thorough understanding of SCC mechanisms of DSS in chloride- and hydrogen sulfide-containing solutions has been useful for material selection in many environments. However, understanding of SCC mechanisms of DSS in sulfide-containing caustic solutions is limited, which has restricted the capacity to optimize process and equipment design in pulp and paper environments. Process environments may contain different concentrations of hydroxide, sulfide, and chloride, altering corrosion and SCC susceptibility of each phase. Crack initiation and growth behavior will also change depending on the relative phase distribution and properties of austenite and ferrite. The role of microstructure and environment on the SCC of standard grade UNS S32205 and lean grade UNS S32101 in hot alkaline-sulfide solution were evaluated in this work using electrochemical, film characterization, mechanical testing, X-ray diffraction, and microscopy techniques. Microstructural aspects, which included residual stress state, phase distribution, phase ratio, and microhardness, were related to the propensity for SCC crack initiation in different simulated alkaline pulping liquors at 170 °C. Other grades of DSS and reference austenitic and superferritic grades of stainless steel were studied using exposure coupons for comparison to understand compositional effects and individual phase susceptibility

  1. Automated Flaw Detection Scheme For Cast Austenitic Stainless Steel Weld Specimens Using Hilbert Huang Transform Of Ultrasonic Phased Array Data

    SciTech Connect

    Khan, T.; Majumdar, Shantanu; Udpa, L.; Ramuhalli, Pradeep; Crawford, Susan L.; Diaz, Aaron A.; Anderson, Michael T.

    2012-01-01

    The objective of this work is to develop processing algorithms to detect and localize the flaws using NDE ultrasonic data. Data was collected using cast austenitic stainless steel (CASS) weld specimens on-loan from the U.S. nuclear power industry’s Pressurized Water Reactor Owners Group (PWROG) specimen set. Each specimen consists of a centrifugally cast stainless steel (CCSS) pipe section welded to a statically cast (SCSS) or wrought (WRSS) section. The paper presents a novel automated flaw detection and localization scheme using low frequency ultrasonic phased array inspection signals in the weld and heat affected zone of the base materials. The major steps of the overall scheme are preprocessing and region of interest (ROI) detection followed by the Hilbert Huang transform (HHT) of A-scans in the detected ROIs. HHT offers time-frequency-energy distribution for each ROI. The accumulation of energy in a particular frequency band is used as a classification feature for the particular ROI.

  2. Title PISC III -- Experience from UT evaluation in cast austenitic stainless steel components

    SciTech Connect

    Zetterwall, T.

    1995-12-01

    This paper deals with the ultrasonic examination and the experience from the Swedish participation in PISC III action No. 4, capability study. It describes the possibilities and the limits of detection with standard- and more advanced techniques in cast stainless steel material. All techniques used are current practiced. The results show that the grain structure and grain sizes has a very important effect on the possibility to make an ultrasonic inspection of these kinds of materials. The results show also that inspections have to be done in two directions and to use an automated scanning devices for evaluation at noise level. The best result was obtained with a standard TRL45{degree}-0,5 MHz transducer for detection of the surface breaking flaws. This study is pertinent for PWR plants.

  3. AN ULTRASONIC PHASED ARRAY EVALUATION OF CAST AUSTENITIC STAINLESS STEEL PRESSURIZER SURGE LINE PIPING WELDS

    SciTech Connect

    Diaz, Aaron A.; Cinson, Anthony D.; Crawford, Susan L.; Moran, Traci L.; Anderson, Michael T.

    2010-07-22

    A set of circumferentially oriented thermal fatigue cracks (TFCs) were implanted into three cast austenitic stainless steel (CASS) pressurizer (PZR) surge-line specimens (pipe-to-elbow welds) that were fabricated using vintage CASS materials formed in the 1970s, and flaw responses from these cracks were used to evaluate detection and sizing performance of the phased-array (PA) ultrasonic testing (UT) methods applied. Four different custom-made PA probes were employed in this study, operating nominally at 800 kHz, 1.0 MHz, 1.5 MHz, and 2.0 MHz center frequencies. The CASS PZR surge-line specimens were polished and chemically etched to bring out the microstructures of both pipe and elbow segments. Additional studies were conducted and documented to address baseline CASS material noise and observe possible ultrasonic beam redirection phenomena.

  4. Investigation of hydrogen induced cracking in 2205 duplex stainless steel in wet H{sub 2}S environments after isothermal treatment at 675, 750 and 900 deg. C

    SciTech Connect

    Sozanska, Maria . E-mail: maria.sozanska@polsl.pl; Klyk-Spyra, Katarzyna

    2006-06-15

    The effect of isothermal treatment (at 675, 750 and 900 deg. C) on HIC (hydrogen induced cracking) in sour environments containing hydrogen sulphide of a 2205 duplex stainless steel has been investigated. The performance and microstructure of failed material were characterized by optical microscopy, scanning electron microscopy and also X-ray diffraction. Two kinds of Cr-, Mo-enriched intermetallic phases, {sigma} and {chi}, were found to precipitate preferentially at {alpha}/{gamma} interfaces and within {alpha} grains after different times of aging in the temperature range of 650-900 deg. C. After performing tests according to the NACE Standard TM 0284 (1987) the specimens were investigated by using quantitative metallography methods. The volume fraction of {sigma} phase was changed with the time of aging and {sigma} phase developed into coarse particles due to the high diffusibility of solute atoms at high temperatures. The variation of size and shape of {sigma} phase particles was obtained by applying different heat treatment conditions to 2205 steel specimens. The results showed that 2205 duplex stainless steel containing nearly 12 vol.% of {sigma} phase in dispersed conditions was resistant to step cracking in wet environments containing hydrogen sulphide. It was highly possible that a crack would propagate faster along the embrittled {sigma} phase. However, very small cracks were found at austenite-ferrite boundaries where o phase particles were also present.

  5. Effect of welding process on the microstructure and properties of dissimilar weld joints between low alloy steel and duplex stainless steel

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Lu, Min-xu; Zhang, Lei; Chang, Wei; Xu, Li-ning; Hu, Li-hua

    2012-06-01

    To obtain high-quality dissimilar weld joints, the processes of metal inert gas (MIG) welding and tungsten inert gas (TIG) welding for duplex stainless steel (DSS) and low alloy steel were compared in this paper. The microstructure and corrosion morphology of dissimilar weld joints were observed by scanning electron microscopy (SEM); the chemical compositions in different zones were detected by energy-dispersive spectroscopy (EDS); the mechanical properties were measured by microhardness test, tensile test, and impact test; the corrosion behavior was evaluated by polarization curves. Obvious concentration gradients of Ni and Cr exist between the fusion boundary and the type II boundary, where the hardness is much higher. The impact toughness of weld metal by MIG welding is higher than that by TIG welding. The corrosion current density of TIG weld metal is higher than that of MIG weld metal in a 3.5wt% NaCl solution. Galvanic corrosion happens between low alloy steel and weld metal, revealing the weakness of low alloy steel in industrial service. The quality of joints produced by MIG welding is better than that by TIG welding in mechanical performance and corrosion resistance. MIG welding with the filler metal ER2009 is the suitable welding process for dissimilar metals jointing between UNS S31803 duplex stainless steel and low alloy steel in practical application.

  6. Development of Stronger and More Reliable Cast Austenitic Stainless Steels (H-Series) Based on Scientific and Design Methodology

    SciTech Connect

    Pankiw, Roman I; Muralidharan, G.; Sikka, Vinod K.

    2006-06-30

    The goal of this project was to increase the high-temperature strength of the H-Series of cast austenitic stainless steels by 50% and the upper use temperature by 86 to 140 degrees fahrenheit (30 to 60 degrees celsius). Meeting this goal is expected to result in energy savings of 35 trillion Btu/year by 2020 and energy cost savings of approximately $230 million/year. The higher-strength H-Series cast stainless steels (HK and HP type) have applications for the production of ethylene in the chemical industry, for radiant burner tubes and transfer rolls for secondary processing of steel in the steel industry, and for many applications in the heat treating industry, including radiant burner tubes. The project was led by Duraloy Technologies, Inc., with research participation by Oak Ridge National Laboratory (ORNL) and industrial participation by a diverse group of companies.

  7. M23C6 carbides and Cr2N nitrides in aged duplex stainless steel: A SEM, TEM and FIB tomography investigation.

    PubMed

    Maetz, J-Y; Douillard, T; Cazottes, S; Verdu, C; Kléber, X

    2016-05-01

    The precipitation evolution during ageing of a 2101 lean duplex stainless steel was investigated, revealing that the precipitate type and morphology depends on the nature of the grain boundary. Triangular M23C6 carbides precipitate only at γ/δ interfaces and rod-like Cr2N nitrides precipitate at both γ/δ and δ/δ interfaces. After 15min of ageing, the M23C6 size no longer evolves, whereas that of the Cr2N continues to evolve. For Cr2N, the morphology is maintained at γ/δ interfaces, whereas percolation occurs to form a continuous layer at δ/δ interfaces. By combining 2D and 3D characterisation at the nanoscale using transmission electron microscopy (TEM) and focused ion beam (FIB) tomography, a complete description of the precipitation evolution was obtained, including the composition, crystallographic structure, orientation relationship with the matrix phases, location, morphology, size and volume fraction. PMID:26925831

  8. Microstructures, Mechanical and Chemical Properties of TLP-Bonded Joints in a Duplex Stainless Steel with Amorphous Ni-Based Insert Alloys

    NASA Astrophysics Data System (ADS)

    Yuan, Xinjian; Kim, Myung Bok; Cho, Young Ho; Kang, Chung Yun

    2012-06-01

    The changes in tensile strength and pitting corrosion resistance of transient liquid-phase (TLP)-bonded joints for a duplex stainless steel with MBF-80, MBF-30, and MBF-35 as functions of holding time and filler were interpreted with respect to the bond microstructure. Using MBF-80 after 300 seconds, the fracture strength of the joint reached the maximum value. The failure was dependent on the interplay between the reduction in residual liquid and the increase in interface precipitates. After 3600 seconds, the joint strength had the minimum value. At the same conditions, the tensile strength for MBF-80 was low compared with MBF-35 and MBF-30. In contrast with the tensile strength, the joint produced with MBF-80 for 3600 seconds exhibited the best corrosion resistance. Among the fillers used, the corrosion resistance of the joint using MBF-80 close to that of the substrate could be related intimately to the existence of Cr in this filler.

  9. Improvement of localised corrosion resistance of AISI 2205 Duplex Stainless Steel joints made by gas metal arc welding under electromagnetic interaction of low intensity

    NASA Astrophysics Data System (ADS)

    García-Rentería, M. A.; López-Morelos, V. H.; García-Hernández, R.; Dzib-Pérez, L.; García-Ochoa, E. M.; González-Sánchez, J.

    2014-12-01

    The resistance to localised corrosion of AISI 2205 duplex stainless steel plates joined by Gas Metal Arc Welding (GMAW) under the effect of electromagnetic interaction of low intensity (EMILI) was evaluated with sensitive electrochemical methods. Welds were made using two shielding gas mixtures: 98% Ar + 2% O2 (M1) and 97% Ar + 3% N2 (M2). Plates were welded under EMILI using the M1 gas with constant welding parameters. The modified microstructural evolution in the high temperature heat affected zone and at the fusion zone induced by application of EMILI during welding is associated with the increase of resistance to localised corrosion of the welded joints. Joints made by GMAW using the shielding gas M2 without the application of magnetic field presented high resistance to general corrosion but high susceptibility to undergo localised attack.

  10. M23C6 carbides and Cr2N nitrides in aged duplex stainless steel: A SEM, TEM and FIB tomography investigation.

    PubMed

    Maetz, J-Y; Douillard, T; Cazottes, S; Verdu, C; Kléber, X

    2016-05-01

    The precipitation evolution during ageing of a 2101 lean duplex stainless steel was investigated, revealing that the precipitate type and morphology depends on the nature of the grain boundary. Triangular M23C6 carbides precipitate only at γ/δ interfaces and rod-like Cr2N nitrides precipitate at both γ/δ and δ/δ interfaces. After 15min of ageing, the M23C6 size no longer evolves, whereas that of the Cr2N continues to evolve. For Cr2N, the morphology is maintained at γ/δ interfaces, whereas percolation occurs to form a continuous layer at δ/δ interfaces. By combining 2D and 3D characterisation at the nanoscale using transmission electron microscopy (TEM) and focused ion beam (FIB) tomography, a complete description of the precipitation evolution was obtained, including the composition, crystallographic structure, orientation relationship with the matrix phases, location, morphology, size and volume fraction.

  11. In situ colonization of marine biofilms on UNS S32760 duplex stainless steel coupons in areas with different water qualities: Implications for corrosion potential behavior

    NASA Astrophysics Data System (ADS)

    Messano, Luciana V. R. de; Ignacio, Barbara L.; Neves, Maria H. C. B.; Coutinho, Ricardo

    2014-09-01

    In the presence of biofilms, stainless steels (SS) exhibits an increase in corrosion potential, called ennoblement. In the present study, the corrosion potential ( E corr) behavior of the duplex SS UNS S32760 was recorded simultaneously with the in situ marine biofilm formation in two areas at Arraial do Cabo, Southeastern Brazil. The biofilm at Forno Harbor (an anthropogenically disturbed area) was characterized by higher relative abundances of Bacteria at day 2, followed by diatoms (especially Navicula sp.) on day 10 and dinoflagellates on day 18, whereas no clear trend was recorded at Cabo Frio Island (an undisturbed area). The ennoblement of E corr values was site-dependent. In a complementary laboratory assay, biofilms were removed and the E corr values registered in sterile conditions for the subsequent 10 days and corroborated in situ results. Understanding biofilms and SS interactions has important implications for materials science and engineering decisions as well as helping to fill in important gaps in this knowledge.

  12. Methods for the In-Situ Characterization of Cast Austenitic Stainless Steel Microstructures

    SciTech Connect

    Ramuhalli, Pradeep; Good, Morris S.; Harris, Robert V.; Bond, Leonard J.; Ruud, Clayton O.; Diaz, Aaron A.; Anderson, Michael T.

    2011-06-29

    Cast austenitic stainless steel (CASS) that was commonly used in U.S. nuclear power plants is a coarse-grained, elastically anisotropic material. Its engineering properties made it a material of choice for selected designs of nuclear power reactor systems. However, the fabrication processes result in a variety of coarse-grain microstructures that make current ultrasonic in-service inspection of components quite challenging. To address inspection needs, new ultrasonic inspection approaches are being sought. However, overcoming the deleterious and variable effects of the microstructure on the interrogating ultrasonic beam may require knowledge of the microstructure, for potential optimization of inspection parameters to enhance the probability of detection (POD). The ability to classify microstructure type (e.g. polycrystalline or columnar) has the potential to guide selection of optimal NDE approaches. This paper discusses the application of ultrasonic and electromagnetic methods for classifying CASS microstructures, when making measurements from the outside surface of the component. Results to date demonstrate the potential of these measurements to discriminate between two consistent microstructures - equiaxed-grain material versus columnar-grain material. The potential for fusion of ultrasonic and electromagnetic measurements for in-situ microstructure characterization in CASS materials will be explored.

  13. Mechanical-property degradation of cast stainless steel components from the Shippingport reactor

    SciTech Connect

    Chopra, O.K.

    1991-10-01

    The mechanical properties of cast stainless steels from the Shippingport reactor have been characterized. Baseline properties for unaged materials were obtained from tests on either recovery-annealed material or material from a cooler region of the component. The materials exhibited modest decrease in impact energy and fracture toughness and a small increase in tensile strength. The fracture toughness J-R curve, J{sub IC} value, tensile flow stress, and Charpy-impact energy of the materials showed very good agreement with estimations based on accelerated laboratory aging studies. The kinetics of thermal embrittlement and degree of embrittlement at saturation, i.e., the minimum impact energy that would be achieved after long-term aging, were established from materials that were aged further in the laboratory at temperatures between 320 and 400{degrees}C. The results showed very good agreement with estimates; the activation energies ranged from 125 to 250 kJ/mole and the minimum room temperature impact energy was <75 J/cm{sup 2}. The estimated impact energy and fracture toughness J-R curve for materials from the Ringhals reactor hot and crossover-leg elbows are also presented.

  14. Effect of heavy ion irradiation on microstructural evolution in CF8 cast austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Chen, Wei-Ying; Li, Meimei; Kirk, Marquis A.; Baldo, Peter M.; Lian, Tiangan

    2016-04-01

    The microstructural evolution in ferrite and austenitic in cast austenitic stainless steel (CASS) CF8, as received or thermally aged at 400 °C for 10,000 h, was followed under TEM with in situ irradiation of 1 MeV Kr ions at 300 and 350 °C to a fluence of 1.9 × 1015 ions/cm2 (∼3 dpa) at the IVEM-Tandem Facility. For the unaged CF8, the irradiation-induced dislocation loops appeared at a much lower dose in the austenite than in the ferrite. At the end dose, the austenite formed a well-developed dislocation network microstructure, while the ferrite exhibited an extended dislocation structure as line segments. Compared to the unaged CF8, the aged specimen appeared to have lower rate of damage accumulation. The rate of microstructural evolution under irradiation in the ferrite was significantly lower in the aged specimen than in the unaged. This difference is attributed to the different initial microstructures in the unaged and aged specimens, which implies that thermal aging and irradiation are not independent but interconnected damage processes.

  15. Technical Letter Report on the Cracking of Irradiated Cast Stainless Steels with Low Ferrite Content

    SciTech Connect

    Chen, Y.; Alexandreanu, B.; Natesan, K.

    2014-11-01

    Crack growth rate and fracture toughness J-R curve tests were performed on CF-3 and CF-8 cast austenite stainless steels (CASS) with 13-14% of ferrite. The tests were conducted at ~320°C in either high-purity water with low dissolved oxygen or in simulated PWR water. The cyclic crack growth rates of CF-8 were higher than that of CF-3, and the differences between the aged and unaged specimens were small. No elevated SCC susceptibility was observed among these samples, and the SCC CGRs of these materials were comparable to those of CASS alloys with >23% ferrite. The fracture toughness values of unirradiated CF-3 were similar between unaged and aged specimens, and neutron irradiation decreased the fracture toughness significantly. The fracture toughness of CF-8 was reduced after thermal aging, and declined further after irradiation. It appears that while lowering ferrite content may help reduce the tendency of thermal aging embrittlement, it is not very effective to mitigate irradiation-induced embrittlement. Under a combined condition of thermal aging and irradiation, neutron irradiation plays a dominant role in causing embrittlement in CASS alloys.

  16. Cracking behavior of thermally aged and irradiated CF-8 cast austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Alexandreanu, B.; Chen, W.-Y.; Natesan, K.; Li, Z.; Yang, Y.; Rao, A. S.

    2015-11-01

    To assess the combined effect of thermal aging and neutron irradiation on the cracking behavior of CF-8 cast austenitic stainless steel, crack growth rate (CGR) and fracture toughness J-R curve tests were carried out on compact-tension specimens in high-purity water with low dissolved oxygen. Both unaged and thermally aged specimens were irradiated at ∼320 °C to 0.08 dpa. Thermal aging at 400 °C for 10,000 h apparently had no effect on the corrosion fatigue and stress corrosion cracking behavior in the test environment. The cracking susceptibility of CF-8 was not elevated significantly by neutron irradiation at 0.08 dpa. Transgranular cleavage-like cracking was the main fracture mode during the CGR tests, and a brittle morphology of delta ferrite was often seen on the fracture surfaces at the end of CGR tests. The fracture toughness J-R curve tests showed that both thermal aging and neutron irradiation can induce significant embrittlement. The loss of fracture toughness due to neutron irradiation was more pronounced in the unaged than aged specimens. After neutron irradiation, the fracture toughness values of the unaged and aged specimens were reduced to a similar level. G-phase precipitates were observed in the aged and irradiated specimens with or without prior aging. The similar microstructural changes resulting from thermal aging and irradiation suggest a common microstructural mechanism of inducing embrittlement in CF-8.

  17. Strengthening of σ phase in a Fe20Cr9Ni cast austenite stainless steel

    SciTech Connect

    Wang, Y.Q.; Han, J.; Yang, B.; Wang, X.T.

    2013-10-15

    The strengthening mechanism of σ phase in a Fe20Cr9Ni cast austenite stainless steel used for primary coolant pipes of nuclear power plants has been investigated. The yield and ultimate tensile strengths of aged specimens increased comparing with those of the unaged ones. It was found that the increase of strengths is due to the hard and brittle (σ + γ{sub 2}) structure which decomposed from α phase in the steel. Fracture surfaces of specimens after in situ tensile test showed that the inhibition of (σ + γ{sub 2}) structure on the dislocation movements was more significant than ferrite although cracks started predominately at σ/γ{sub 2} interfaces. The (σ + γ{sub 2}) structure behaves like a fiber reinforced composite material. - Highlights: • The strengthening mechanism of σ phase in a Fe20Cr9Ni CASS is investigated. • The yield and ultimate tensile strengths increase with increasing of σ phase. • The increase of strengths is due to hard and brittle (σ + γ{sub 2}) structure. • The (σ + γ{sub 2}) structure in CASS behaves like a fibre reinforced composite material. • The σ/γ{sub 2} and α/σ/γ{sub 2} boundaries hinder the movement of dislocation.

  18. Lamb wave inspection for large cracks in centrifugally cast stainless steel: Interim report

    SciTech Connect

    Not Available

    1988-08-01

    The objective of the present research project is to develop an inspection technique to detect and size large-scale cracks in centrifugally cast stainless steel (CCSS) pipes. This technique is based on the use of Lamb waves, or generally the resonant modes of propagation in the considered geometry, to circumvent the difficulties encountered when the conventional ultrasonic bulk waves are used to inspect the anisotropic, highly absorptive CCSS material. The research activities in 1987 were focused on probe design, Lamb-wave mode selection and excitation, detection mechanism, and anisotropy and curvature effects. The optimal design of a laboratory search unit was determined to be a tandem dual-element system built on the liquid-wedge principle. A reliable mechanism, which features a strong amplitude reduction when the search unit is scanned over a crack, was identified for crack detection and location. The preliminary experimental and analytical findings indicate that the best resonant modes were identified to be the four lowest modes in light of their excitability and minimization of the anisotropy effect. Finally, for typical geometrical dimensions under consideration, the curvature effect was found to be minimal.

  19. Analysis of cracking phenomena in continuous casting of 1Cr13 stainless steel billets with final electromagnetic stirring

    NASA Astrophysics Data System (ADS)

    Xu, Yu; Xu, Rong-jun; Fan, Zheng-jie; Li, Cheng-bin; Deng, An-yuan; Wang, En-gang

    2016-05-01

    Solidification cracking that occurs during continuous casting of 1Cr13 stainless steel was investigated with and without final electromagnetic stirring (F-EMS). The results show that cracks initiates and propagates along the grain boundaries where the elements of carbon and sulfur are enriched. The final stirrer should be appropriately placed at a location that is 7.5 m away from the meniscus, and the appropriate thickness of the liquid core in the stirring zone is 50 mm. As a stirring current of 250 A is imposed, it can promote columnar-equiaxed transition, decrease the secondary dendrite arm spacing, and reduce the segregation of both carbon and sulfur. F-EMS can effectively decrease the amount of cracks in 1Cr13 stainless steel.

  20. Internal Crack Propagation in a Continuously Cast Austenitic Stainless Steel Analyzed by Actual Residual Stress Tensor Distributions

    NASA Astrophysics Data System (ADS)

    Saito, Youichi; Tanaka, Shun-Ichiro

    2016-04-01

    Initiation, propagation, and termination of internal cracks in a continuously cast austenitic stainless steel has been investigated with emphasis on stress loading of the solidified shell during casting. Cracks were formed at the center of the slab, parallel to the width of the cast, and were observed near the narrow faces. Optimized two-dimensional X-ray diffraction method was employed to measure residual stress tensor distributions around the cracks in the as-cast slab with coarse and strongly preferentially oriented grains. The tensor distributions had a sharp peak, as high as 430 MPa, at the crack end neighboring the columnar grains. On the other hand, lower values were measured at the crack end neighboring the equiaxed grains, where the local temperatures were higher during solidification. The true residual stress distributions were determined by evaluating the longitudinal elastic constant for each measured position, resulting in more accurate stress values than before. Electron probe micro-analysis at the terminal crack position showed that Ni, Ti, and Si were concentrated at the boundaries of the equiaxed grains, where the tensile strength was estimated to be lower than at the primary grains. A model of the crack formation and engineering recommendations to reduce crack formation are proposed.

  1. Investigation of the Kinetics of the Ferrite/Austenite Phase Transformation in the HAZ of a 2205 Duplex Stainless Steel Weldment

    SciTech Connect

    Palmer, T A; Elmer, J W; Wong, J; Babu, S S; Vitek, J M

    2002-03-14

    A semi-quantitative map based on a series of spatially resolved X-ray diffraction (SRXRD) scans shows the progression of the ferrite ({delta})/austenite ({gamma}) phase balance throughout the HAZ during GTA welding of a 2205 duplex stainless steel (DSS). This map shows an unexpected decrease in the ferrite fraction on heating, followed by a recovery to the original ferrite fraction on cooling at locations within the HAZ. Even though such behavior is supported by thermodynamic calculations, it has not been confirmed by either experimental methods or have the kinetics been evaluated. Both Gleeble thermal simulations and time resolved x-ray diffraction measurements on spot welds in the 2205 DSS provide further evidence for this rather low-temperature transformation. On the other hand, calculations of the diffusion of alloying elements across the 6/y interface under a variety of conditions shed no further light on the driving force for this transformation. Further work on the mechanisms and driving forces for this transformation is on-going.

  2. Surface modification of 2205 duplex stainless steel by low temperature salt bath nitrocarburizing at 430 °C

    NASA Astrophysics Data System (ADS)

    Huang, Runbo; Wang, Jun; Zhong, Si; Li, Mingxing; Xiong, Ji; Fan, Hongyuan

    2013-04-01

    2205 stainless steel was modified by salt bath nitrocarburizing at 430 °C in this study. The microstructure, surface hardness and erosion-corrosion resistance were systematically evaluated. Salt bath nitrocarburizing at 430 °C can form a nitrocarburized layer, and with the treated time prolong, the thickness of the layer increased. By nitrocarburizing within 8 h, only expanded austenite (S phase) formed. With treated time increased, CrN gradually diffused from the places where there were ferrite grains in the layer before nitrocarburizing. Besides, the depth increased with the nitrocarburized time and the layer grew approximately conforms to the parabolic rate law. Salt bath nitrocarburizing can effectively improve the surface hardness of 2205 DSS. The erosion-corrosion resistance was improved by salt bath nitrocarburizing and the 16 h treated sample had the best erosion-corrosion behavior.

  3. Sensitization phenomena on aged SAF 2205 duplex stainless steel and their control using the electrochemical potentiokinetic reactivation test

    SciTech Connect

    Angelini, E.; Benedetti, B. de; Maizza, G.; Rosalbino, F. . Dept. of Materials Science and Chemical Engineering)

    1999-06-01

    Microstructural changes and resulting properties were studied for SAF 2205 (UNS S31803) austeno-ferritic stainless steel (SS) aged between 700 C and 900 C for up to 2 weeks and then water-quenched. Quantitative metallography coupled with x-ray diffraction techniques were adopted to follow ferrite ([alpha]) transformation with subsequent formation of secondary austenite ([gamma][sub 2]) and sigma ([sigma]) phase. The kinetic model of a transformation was interpreted in the form of an Avrami-type expression. The electrochemical potentiokinetic reactivation (EPR) test was used to evaluate the degree of sensitization of the aged specimens. Results were compared with results from the corrosion test in boiling nitric acid (HNO[sub 3]). Influences of the transformation of ferrite into austenite, sigma phase, and of other microstructural variations such as chromium nitride (Cr[sub 2]N) precipitation on stability of the passive film were shown. The susceptibility to intergranular corrosion phenomena was caused by chromium depletion caused by sigma phase precipitation, while chromium nitrides appeared less harmful. Results were expressed as an isocharge line diagram that allowed concise identification of sensitization and desensitization ranges.

  4. Energy Saving Melting and Revert Reduction (E-SMARRT): Optimization of Heat Treatments on Stainless Steel Castings for Improved Corrosion Resistance and Mechanical Properties

    SciTech Connect

    John N. DuPont; Jeffrey D. Farren; Andrew W. Stockdale; Brett M. Leister

    2012-06-30

    It is commonly believed that high alloy steel castings have inferior corrosion resistance to their wrought counterparts as a result of the increased amount of microsegregation remaining in the as-cast structure. Homogenization and dissolution heat treatments are often utilized to reduce or eliminate the residual microsegregation and dissolve the secondary phases. Detailed electron probe microanalysis (EPMA) and light optical microscopy (LOM) were utilized to correlate the amount of homogenization and dissolution present after various thermal treatments with calculated values and with the resultant corrosion resistance of the alloys.The influence of heat treatment time and temperature on the homogenization and dissolution kinetics were investigated using stainless steel alloys CN3MN and CK3MCuN. The influence of heat treatment time and temperature on the impact toughness and corrosion reistance of cast stainless steel alloys CF-3, CF-3M, CF-8, and CF-8M was also investigated.

  5. Development of Stronger and More Reliable Cast Austenitic Stainless Steels (H-Series) Based on Scientific Design Methodology

    SciTech Connect

    Muralidharan, G.; Sikka, V.K.; Pankiw, R.I.

    2006-04-15

    The goal of this program was to increase the high-temperature strength of the H-Series of cast austenitic stainless steels by 50% and upper use temperature by 86 to 140 F (30 to 60 C). Meeting this goal is expected to result in energy savings of 38 trillion Btu/year by 2020 and energy cost savings of $185 million/year. The higher strength H-Series of cast stainless steels (HK and HP type) have applications for the production of ethylene in the chemical industry, for radiant burner tubes and transfer rolls for secondary processing of steel in the steel industry, and for many applications in the heat-treating industry. The project was led by Duraloy Technologies, Inc. with research participation by the Oak Ridge National Laboratory (ORNL) and industrial participation by a diverse group of companies. Energy Industries of Ohio (EIO) was also a partner in this project. Each team partner had well-defined roles. Duraloy Technologies led the team by identifying the base alloys that were to be improved from this research. Duraloy Technologies also provided an extensive creep data base on current alloys, provided creep-tested specimens of certain commercial alloys, and carried out centrifugal casting and component fabrication of newly designed alloys. Nucor Steel was the first partner company that installed the radiant burner tube assembly in their heat-treating furnace. Other steel companies participated in project review meetings and are currently working with Duraloy Technologies to obtain components of the new alloys. EIO is promoting the enhanced performance of the newly designed alloys to Ohio-based companies. The Timken Company is one of the Ohio companies being promoted by EIO. The project management and coordination plan is shown in Fig. 1.1. A related project at University of Texas-Arlington (UT-A) is described in Development of Semi-Stochastic Algorithm for Optimizing Alloy Composition of High-Temperature Austenitic Stainless Steels (H-Series) for Desired

  6. Field Evaluations of Low-Frequency SAFT-UT on Cast Stainless Steel and Dissimilar Metal Weld Components

    SciTech Connect

    Diaz, Aaron A.; Harris, R. V.; Doctor, Steven R.

    2008-11-01

    This report documents work performed at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington, and at the Electric Power Research Institute's (EPRI) Nondestructive Examination (NDE) Center in Charlotte, North Carolina, on evalutating a low frequency ultrasonic inspection technique used for examination of cast stainless steel (CSS) and dissimilar metal (DMW) reactor piping components. The technique uses a zone-focused, multi-incident angle, low frequency (250-450 kHz) inspection protocol coupled with the synthetic aperture focusing technique (SAFT). The primary focus of this work is to provide information to the United States Nuclear Regulatory Commission on the utility, effectiveness and reliability of ultrasonic testing (UT) inspection techniques as related to the inservice ultrasonic inspection of coarse grained primary piping components in pressurized water reactors (PWRs).

  7. Observations of Ferrite/Austenite Transformations in the Heat Affected Zone of 2205 Duplex Stainless Steel Spot Welds Using Time Resolved X-Ray Diffraction

    SciTech Connect

    Palmer, T; Elmer, J; Babu, S

    2003-10-29

    Time Resolved X-Ray Diffraction (TRXRD) measurements are made in the Heat Affected Zone (HAZ) of 2205 Duplex Stainless Steel (DSS) spot welds. Both the {gamma} {yields} {delta} and {delta} {yields} {gamma} transformations are monitored as a function of time during the rapid spot weld heating and cooling cycles. These observations are then correlated with calculated thermal cycles. Where the peak temperatures are highest ({approx}1342 C), the {gamma} {yields} {delta} transformation proceeds to completion, leaving a ferritic microstructure at the end of heating. With lower peak temperatures, the {gamma} {yields} {delta} transformation proceeds to only partial completion, resulting in a microstructure containing both transformed and untransformed austenite. Further analyses of the individual diffraction patterns show shifts in the peak positions and peak widths as a function of both time and temperature. In addition, these changes in the peak characteristics are correlated with measured changes in the ferrite volume fraction. Such changes in the peak positions and widths during the {gamma} {yields} {delta} transformation provide an indication of changes occurring in each phase. These changes in peak properties can be correlated with the diffusion of nitrogen and other substitutional alloying elements, which are recognized as the primary mechanisms for this transformation. Upon cooling, the {delta} {yields} {gamma} transformation is observed to proceed from both the completely and partially transformed microstructural regions in the TRXRD data. An examination of the resulting microstructures confirms the TRXRD observation as the evidence shows that austenite both nucleates and grows from the ferritic microstructure at locations closest to the fusion zone boundary and grows from untransformed austenite grains at locations further from this boundary.

  8. Effect of oxygen on weld shape and crystallographic orientation of duplex stainless steel weld using advanced A-TIG (AA-TIG) welding method

    SciTech Connect

    Zou, Ying Ueji, Rintaro; Fujii, Hidetoshi

    2014-05-01

    The double-shielded advanced A-TIG (AA-TIG) welding method was adopted in this study for the welding of the SUS329J4L duplex stainless steel with the shielding gases of different oxygen content levels. The oxygen content in the shielding gas was controlled by altering the oxygen content in the outer layer gas, while the inner layer remained pure argon to suppress oxidation on the tungsten electrode. As a result, a deep weld penetration was obtained due to the dissolution of oxygen into the weld metals. Additionally, the microstructure of the weld metal was changed by the dissolution of oxygen. The austenite phase at the ferrite grain boundary followed a Kurdjumov–Sachs (K–S) orientation relationship with the ferrite matrix phase at any oxide content. On the other hand, the orientation relationship between the intragranular austenite phase and the ferrite matrix phase exhibited different patterns under different oxygen content levels. When there was little oxide in the fusion zone, only a limited part of the intragranular austenite phase and the ferrite matrix phase followed the K–S orientation relationship. With the increase of the oxide, the correspondence of the K–S relationship increased and fit very well in the 2.5% O{sub 2} shielded sample. The investigation of this phenomenon was carried out along with the nucleation mechanisms of the intragranular austenite phases. - Highlights: • Weld penetration increased with the increase of the oxygen content. • Average diameter and number density of oxide were changed by the oxygen content. • K-S relationship of Widmanstätten austenite/ferrite wasn’t varied by oxide. • Orientation relationship of intragranular austenite/ferrite was varied by oxide.

  9. Microstructural Evolution of an Al-Alloyed Duplex Stainless Steel During Tensile Deformation Between 77 K and 473 K (-196 °C and 200 °C)

    NASA Astrophysics Data System (ADS)

    Rahimi, Reza; Ullrich, Christiane; Rafaja, David; Biermann, Horst; Mola, Javad

    2016-06-01

    Tensile deformation behavior of an Al-alloyed Fe-17Cr-6Mn-4Al-3Ni-0.45C (mass pct) duplex stainless steel containing approximately 20 vol pct ferrite was studied in the temperature range from 77 K to 473 K (-196 °C to 200 °C). While the elongation exhibited a maximum near room temperature, the yield strength continuously increased at lower tensile test temperatures. According to the microstructural examinations, the twinning-induced plasticity and the dislocation cell formation were the dominant deformation mechanisms in the austenite and ferrite, respectively. Reduction of the tensile ductility at T < 273 K (0 °C) was attributed to the ready material decohesion at the ferrite/austenite boundaries. Tensile testing at 473 K (200 °C) was associated with the serrated flow which was ascribed to the Portevin-Le Chatelier effect. Due to a rise in the stacking fault energy of austenite, the occurrence of mechanical twinning was impeded at higher tensile test temperatures. Furthermore, the evolution of microstructural constituents at room temperature was studied by interrupted tensile tests. The deformation in the austenite phase started with the formation of Taylor lattices followed by mechanical twinning at higher strains/stresses. In the ferrite phase, on the other hand, the formation of dislocation cells, cell refinement, and microbands formation occurred in sequence during deformation. Microhardness evolution of ferrite and austenite in the interrupted tensile test specimens implied a higher strain-hardening rate for the austenite as it clearly became the harder phase at higher tensile strain levels.

  10. Temperature effects on the static and dynamic fracture behaviors of low-silicon CA-15 tempered stainless steel castings

    NASA Astrophysics Data System (ADS)

    Hsu, Cheng-Hsun; Teng, Hwei-Yuan

    2005-04-01

    In this research we studied the effect of testing temperature on both static and dynamic fracturing behaviors of low-silicon CA-15 martensitic stainless steel (MSS) castings after austenitizing and tempering treatments. The results showed that the material's microstructure was influenced by heat treatment and various testing temperatures would cause different fracturing mechanisms. In static tensile tests, the 573-673 K tempered specimens occurred secondary strengthening at 423 K and 298 K testing temperatures. However, there is a contrast of weakening occurred at 123 K for the same type of tempered samples. The phenomenon was mainly triggered by local cracking at the ferrite/martensitic interface and incoherent precipitate site in the materials because of the existence of shrinkage stress under subzero temperature. In the dynamic strain-rate tests, impact embrittlement occurred in the 573-673 K tempered samples as a result of the tempered martensite embrittlement (TME) phenomenon. The ductile-to-brittle transition temperature (DBTT) of the tempered material was obviously lower than that of the as-cast material. Also, optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were performed to correlate the properties attained to the microstructural observation.

  11. Heat and corrosion resistant cast CN-12 type stainless steel with improved high temperature strength and ductility

    DOEpatents

    Mazias, Philip J.; McGreevy, Tim; Pollard,Michael James; Siebenaler, Chad W.; Swindeman, Robert W.

    2007-08-14

    A cast stainless steel alloy and articles formed therefrom containing about 0.5 wt. % to about 10 wt. % manganese, 0.02 wt. % to 0.50 wt. % N, and less than 0.15 wt. % sulfur provides high temperature strength both in the matrix and at the grain boundaries without reducing ductility due to cracking along boundaries with continuous or nearly-continuous carbides. Alloys of the present invention also have increased nitrogen solubility thereby enhancing strength at all temperatures because nitride precipitates or nitrogen porosity during casting are not observed. The solubility of nitrogen is dramatically enhanced by the presence of manganese, which also retains or improves the solubility of carbon thereby providing additional solid solution strengthening due to the presence of manganese and nitrogen, and combined carbon. Such solution strengthening enhances the high temperature precipitation-strengthening benefits of fine dispersions of NbC. Such solid solution effects also enhance the stability of the austenite matrix from resistance to excess sigma phase or chrome carbide formation at higher service temperatures. The presence of sulfides is substantially eliminated.

  12. Long-term oxidation of candidate cast iron and stainless steel exhaust system alloys from 650 to 800 °C in air with water vapor

    SciTech Connect

    Brady, Michael P.; Muralidharan, Govindarajan; Leonard, Donovan .; Haynes, James A.; Weldon, R. G.; England, R. D.

    2014-08-29

    Here, the oxidation behavior of SiMo cast iron, Ni-resist D5S cast iron, cast chromia-forming austenitic stainless steels of varying Cr/Ni content based on CF8C plus, HK, and HP, and a developmental cast alumina-forming austenitic (AFA) stainless steel of interest for diesel exhaust system components were studied for up to 5000 h at 650-800 °C in air with 10% H2O. At 650 °C, the Ni-resist D5S exhibited moderately better oxidation resistance than did the SiMo cast iron. However, the D5S suffered from oxide scale spallation issues at 700 °C and higher, whereas the oxide scales formed on SiMo cast iron remained adherent from 700-800 °C despite oxide scales hundreds of microns thick. The oxidation of the SiMo cast iron exhibited unusual temperature dependence, with periods of slower oxidation kinetics at 750-800 °C compared to 650-700 °C due to continuous silica-rich scale formation at the higher temperatures. The oxidation of the cast chromia-forming austenitics trended with the level of Cr and Ni additions, with small mass losses consistent with Cr oxy-hydroxide volatilization processes for the higher 25Cr/25-35Ni HK and HP type alloys, and transition to rapid Fe-base oxide formation and scale spallation in the lower 19Cr/12Ni CF8C plus type alloy. In contrast, small positive mass changes consistent with protective alumina scale formation were observed for the cast AFA alloy under all conditions studied. Implications of these findings for diesel exhaust system components are discussed.

  13. Long-term oxidation of candidate cast iron and stainless steel exhaust system alloys from 650 to 800 °C in air with water vapor

    DOE PAGES

    Brady, Michael P.; Muralidharan, Govindarajan; Leonard, Donovan .; Haynes, James A.; Weldon, R. G.; England, R. D.

    2014-08-29

    Here, the oxidation behavior of SiMo cast iron, Ni-resist D5S cast iron, cast chromia-forming austenitic stainless steels of varying Cr/Ni content based on CF8C plus, HK, and HP, and a developmental cast alumina-forming austenitic (AFA) stainless steel of interest for diesel exhaust system components were studied for up to 5000 h at 650-800 °C in air with 10% H2O. At 650 °C, the Ni-resist D5S exhibited moderately better oxidation resistance than did the SiMo cast iron. However, the D5S suffered from oxide scale spallation issues at 700 °C and higher, whereas the oxide scales formed on SiMo cast iron remainedmore » adherent from 700-800 °C despite oxide scales hundreds of microns thick. The oxidation of the SiMo cast iron exhibited unusual temperature dependence, with periods of slower oxidation kinetics at 750-800 °C compared to 650-700 °C due to continuous silica-rich scale formation at the higher temperatures. The oxidation of the cast chromia-forming austenitics trended with the level of Cr and Ni additions, with small mass losses consistent with Cr oxy-hydroxide volatilization processes for the higher 25Cr/25-35Ni HK and HP type alloys, and transition to rapid Fe-base oxide formation and scale spallation in the lower 19Cr/12Ni CF8C plus type alloy. In contrast, small positive mass changes consistent with protective alumina scale formation were observed for the cast AFA alloy under all conditions studied. Implications of these findings for diesel exhaust system components are discussed.« less

  14. Automated flaw detection scheme for cast austenitic stainless steel weld specimens using Hilbert-Huang transform of ultrasonic phased array data

    SciTech Connect

    Khan, Tariq; Majumdar, Shantanu; Udpa, Lalita; Ramuhalli, Pradeep; Crawford, Susan; Diaz, Aaron; Anderson, Michael T.

    2012-05-17

    The objective of this work is to develop processing algorithms to detect and localize flaws using ultrasonic phased-array data. Data was collected on cast austenitic stainless stell (CASS) weld specimens onloan from the U.S. nuclear power industry' Pressurized Walter Reactor Owners Group (PWROG) traveling specimen set. Each specimen consists of a centrifugally cast stainless stell (CCSS) pipe section welded to a statically cst(SCSS) or wrought (WRSS) section. The paper presents a novel automated flaw detection and localization scheme using low frequency ultrasonic phased array inspection singals from the weld and heat affected zone of the based materials. The major steps of the overall scheme are preprocessing and region of interest (ROI) detection followed by the Hilbert-Huang transform (HHT) of A-scans in the detected ROIs. HHT offers time-frequency-energy distribution for each ROI. The Accumulation of energy in a particular frequency band is used as a classification feature for the particular ROI.

  15. Automated flaw detection scheme for cast austenitic stainless stell weld specimens using Hilbert-Huang transform of ultrasonic phased array data

    NASA Astrophysics Data System (ADS)

    Khan, Tariq; Majumdar, Shantanu; Udpa, Lalita; Ramuhalli, Pradeep; Crawford, Susan; Diaz, Aaron; Anderson, Michael T.

    2012-05-01

    The objective of this work is to develop processing algorithms to detect and localize flaws using ultrasonic phased-array data. Data was collected on cast austenitic stainless stell (CASS) weld specimens onloan from the U.S. nuclear power industry' Pressurized Walter Reactor Owners Group (PWROG) traveling specimen set. Each specimen consists of a centrifugally cast stainless stell (CCSS) pipe section welded to a statically cst(SCSS) or wrought (WRSS) section. The paper presents a novel automated flaw detection and localization scheme using low frequency ultrasonic phased array inspection singals from the weld and heat affected zone of the based materials. The major steps of the overall scheme are preprocessing and region of interest (ROI) detection followed by the Hilbert-Huang transform (HHT) of A-scans in the detected ROIs. HHT offers time-frequency-energy distribution for each ROI. The Accumulation of energy in a particular frequency band is used as a classification feature for the particular ROI.

  16. Heat treatment of investment cast PH 13-8 Mo stainless steel: Part II. Isothermal aging kinetics

    NASA Astrophysics Data System (ADS)

    Robino, C. V.; Cieslak, M. J.; Hochanadel, P. W.; Edwards, G. R.

    1994-04-01

    The hardening response of investment cast PH 13-8 Mo stainless steel has been evaluated by hardness measurements following aging in the temperature range normally specified for this alloy (510 °C to 593 °C). A new relationship between fraction transformed and hardness was developed, and analysis of the data in terms of the kinetics of precipitation, in a manner similar to that frequently applied to other precipitation-hardenable martensitic steels, yielded low time exponents and a low value for the apparent activation energy. The values of the time exponents were 0.49, 0.37, 0.56, and 0.53 at 510 °C, 538 °C, 566 °C, and 593 °C, respectively, and that for the apparent activation energy was 139 kJ/mole. As has been proposed for other maraging type steels, these estimates suggest that Β-NiAl precipitates along or near dislocations and that growth of the precipitates is dominated by dislocation pipe diffusion. However, these predictions were neither supported nor refuted by transmission electron microscopy (TEM) because of difficulties in imaging the Β-NiAl precipitates at the aging times and temperatures used. Further, analysis of the data using the formalism of Wert and Zener for the growth of precipitates with interfering diffusion fields indicated that the estimates of fraction transformed from hardness data are not fully appropriate for maraging type steels. Consideration of the nature of the Avrami analysis and the electron microscopy results suggests that other phenomena, including dislocation recovery and reversion of martensite to austenite, occur at rates sufficient to convolute the Avrami analysis. It is further suggested that these results cast doubt on the fundamental implications of previous analyses of precipitation kinetics in age-hardening martensitic steels. Although the Avrami analysis was found not to provide a tenable description of the precipitation kinetics, it does provide a reasonable methodology for portrayal of the hardening response

  17. Ultrasonic Characterization of Cast Austenitic Stainless Steel Microstructure: Discrimination between Equiaxed- and Columnar-Grain Material – An Interim Study

    SciTech Connect

    Ramuhalli, Pradeep; Good, Morris S.; Diaz, Aaron A.; Anderson, Michael T.; Watson, Bruce E.; Peters, Timothy J.; Dixit, Mukul; Bond, Leonard J.

    2009-10-27

    Ultrasonic nondestructive evaluation (NDE) and inspection of cast austenitic stainless steel (CASS) components used in the nuclear power industry is neither as effective nor reliable as is needed due to detrimental effects upon the interrogating ultrasonic beam and interference from ultrasonic backscatter. The root cause is the coarse-grain microstructure inherent to this class of materials. Some ultrasonic techniques perform better for particular microstructural classifications and this has led to the hypothesis that an ultrasonic inspection can be optimized for a particular microstructural class, if a technique exists to reliably classify the microstructure for feedback to the inspection. This document summarizes scoping experiments of in-situ ultrasonic methods for classification and/or characterization of the material microstructures in CASS components from the outside surface of a pipe. The focus of this study was to evaluate ultrasonic methods and provide an interim report that documents results and technical progress. An initial set of experiments were performed to test the hypothesis that in-service characterization of cast austenitic stainless steel (CASS) is feasible, and that, if reliably performed, such data would provide real-time feedback to optimize in-service inspections in the field. With this objective in mind, measurements for the experiment were restricted to techniques that should be robust if carried forward to eventual field implementation. Two parameters were investigated for their ability to discriminate between different microstructures in CASS components. The first parameter was a time-of-flight ratio of a normal incidence shear wave to that of a normal incidence longitudinal wave (TOFRSL). The ratio removed dependency on component thickness which may not be accurately reported in the field. The second parameter was longitudinal wave attenuation. The selected CASS specimens provided five equiaxed-grain material samples and five columnar

  18. Heat treatment of investment cast PH 13-8 Mo stainless steel: Part I. Mechanical properties and microstructure

    NASA Astrophysics Data System (ADS)

    Hochanadel, P. W.; Edwards, G. R.; Robino, C. V.; Cieslak, M. J.

    1994-04-01

    The microstructure of investment cast PH 13-8 Mo stainless steel heat-treated to various conditions was studied using light and electron microscopy, electron probe microanalysis, and Mössbauer spectroscopy. The mechanical properties were investigated by using uniaxial tensile testing, hardness testing, and Charpy impact testing. The Β-NiAl strengthening precipitates, though detectable by electron diffraction, were difficult to resolve by transmission electron microscopy (TEM) in specimens aged at low temperatures (566 °C and below). A high dislocation density was observed in the lath martensitic structure. The higher strength and lower ductility observed at low aging temperatures was attributed to both the high dislocation density and the precipitation of Β-NiAl. When samples were aged at high temperatures (> 566 °C), a lower dislocation density and a reverted austenite fraction on the order of 15 pct were observed. Spherical Β-NiAl precipitates were observed in the overaged condition. The decrease in strength and corresponding increase in ductility observed in samples aged at temperatures above 566 °C were attributed to the reverted austenite and recovery. Mechanical properties were improved when the homogenizing temperature and time were increased. Electron probe microanalysis quantified the increased homogeneity realized by increasing homogenizing temperature and time. Elimination of the refrigeration step, which normally follows the solution treatment, did not degrade the mechanical properties. Mössbauer spectroscopy showed only minor decreases in the fraction of retained austenite when refrigeration followed the solution treatment.

  19. Heat and corrosion resistant cast CF8C stainless steel with improved high temperature strength and ductility

    DOEpatents

    Maziasz, Philip J.; McGreevy, Tim; Pollard, Michael James; Siebenaler, Chad W.; Swindeman, Robert W.

    2010-08-17

    A CF8C type stainless steel alloy and articles formed therefrom containing about 18.0 weight percent to about 22.0 weight percent chromium and 11.0 weight percent to about 14.0 weight percent nickel; from about 0.05 weight percent to about 0.15 weight percent carbon; from about 2.0 weight percent to about 10.0 weight percent manganese; and from about 0.3 weight percent to about 1.5 weight percent niobium. The present alloys further include less than 0.15 weight percent sulfur which provides high temperature strength both in the matrix and at the grain boundaries without reducing ductility due to cracking along boundaries with continuous or nearly-continuous carbides. The disclosed alloys also have increased nitrogen solubility thereby enhancing strength at all temperatures because nitride precipitates or nitrogen porosity during casting are not observed. The solubility of nitrogen is dramatically enhanced by the presence of manganese, which also retains or improves the solubility of carbon thereby providing additional solid solution strengthening due to the presence of manganese and nitrogen, and combined carbon.

  20. Modeling of ultrasonic propagation in heavy-walled centrifugally cast austenitic stainless steel based on EBSD analysis.

    PubMed

    Chen, Yao; Luo, Zhongbing; Zhou, Quan; Zou, Longjiang; Lin, Li

    2015-05-01

    The ultrasonic inspection of heavy-walled centrifugally cast austenitic stainless steel (CCASS) is challenging due to the complex metallurgical structure. Numerical modeling could provide quantitative information on ultrasonic propagation and plays an important role in developing advanced and reliable ultrasonic inspection techniques. But the fundamental obstacle is the accurate description of the complex metallurgical structure. To overcome this difficulty, a crystal orientation map of a CCASS specimen in the 96 mm × 12 mm radial-axial cross section was acquired based on the electron backscattered diffraction (EBSD) technique and it was used to describe the coarse-grained structure and grain orientation. A model of ultrasonic propagation for CCASS was built according to the EBSD map. The ultrasonic responses of the CCASS sample were also tested. Some experimental phenomena such as structural noise and signal distortion were reproduced. The simulated results showed a good consistence with the experiments. The modeling method is expected to be effective for the precise interpretation of ultrasonic propagation in the polycrystalline structures of CCASS.

  1. Heat and corrosion resistant cast CF8C stainless steel with improved high temperature strength and ductility

    DOEpatents

    Maziasz, Philip J.; McGreevy, Tim; Pollard, Michael James; Siebenaler, Chad W.; Swindeman, Robert W.

    2006-12-26

    A CF8C type stainless steel alloy and articles formed therefrom containing about 18.0 weight percent to about 22.0 weight percent chromium and 11.0 weight percent to about 14.0 weight percent nickel; from about 0.05 weight percent to about 0.15 weight percent carbon; from about 2.0 weight percent to about 10.0 weight percent manganese; and from about 0.3 weight percent to about 1.5 weight percent niobium. The present alloys further include less than 0.15 weight percent sulfur which provides high temperature strength both in the matrix and at the grain boundaries without reducing ductility due to cracking along boundaries with continuous or nearly-continuous carbides. The disclosed alloys also have increased nitrogen solubility thereby enhancing strength at all temperatures because nitride precipitates or nitrogen porosity during casting are not observed. The solubility of nitrogen is dramatically enhanced by the presence of manganese, which also retains or improves the solubility of carbon thereby providing additional solid solution strengthening due to the presence of manganese and nitrogen, and combined carbon.

  2. Modeling of ultrasonic propagation in heavy-walled centrifugally cast austenitic stainless steel based on EBSD analysis.

    PubMed

    Chen, Yao; Luo, Zhongbing; Zhou, Quan; Zou, Longjiang; Lin, Li

    2015-05-01

    The ultrasonic inspection of heavy-walled centrifugally cast austenitic stainless steel (CCASS) is challenging due to the complex metallurgical structure. Numerical modeling could provide quantitative information on ultrasonic propagation and plays an important role in developing advanced and reliable ultrasonic inspection techniques. But the fundamental obstacle is the accurate description of the complex metallurgical structure. To overcome this difficulty, a crystal orientation map of a CCASS specimen in the 96 mm × 12 mm radial-axial cross section was acquired based on the electron backscattered diffraction (EBSD) technique and it was used to describe the coarse-grained structure and grain orientation. A model of ultrasonic propagation for CCASS was built according to the EBSD map. The ultrasonic responses of the CCASS sample were also tested. Some experimental phenomena such as structural noise and signal distortion were reproduced. The simulated results showed a good consistence with the experiments. The modeling method is expected to be effective for the precise interpretation of ultrasonic propagation in the polycrystalline structures of CCASS. PMID:25670411

  3. Phased Array Ultrasonic Sound Field Mapping through Large-Bore Coarse Grained Cast Austenitic Stainless Steel (CASS) Components

    SciTech Connect

    Crawford, Susan L.; Cinson, Anthony D.; Prowant, Matthew S.; Coble, Jamie B.; Diaz, Aaron A.; Anderson, Michael T.

    2012-09-01

    A sound field beam mapping exercise was conducted to assist in understanding the effects of coarse-grained microstructures found in cast austenitic stainless steel (CASS) materials on acoustic longitudinal wave propagation. Ultrasonic laboratory measurements were made on three specimens representing four different grain structures. Phased array (PA) probes were fixed on each specimen surface and excited in the longitudinal mode at specific angles while a point receiver was scanned in a raster pattern over the end of the specimen, generating a transmitted sound field image. Three probes operating at nominal frequencies of 0.5, 0.8, and 1.0 MHz were used. A 6.4 mm (0.25-in.) thick slice was removed from the specimen end and beam mapping was repeated three times, yielding four full sets of beam images. Data were collected both with a constant part path for each configuration (probe, specimen and slice, angle, etc.) and with a variable part path (fixed position on the surface). The base specimens and slices were then polished and etched to reveal measureable grain microstructures that were compared to the sound field interactions and scattering effects seen in the collected data.

  4. Cast, heat-resistant austenitic stainless steels having reduced alloying element content

    DOEpatents

    Muralidharan, Govindarajan [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Maziasz, Philip J [Oak Ridge, TN; Pankiw, Roman I [Greensburg, PA

    2010-07-06

    A cast, austenitic steel composed essentially of, expressed in weight percent of the total composition, about 0.4 to about 0.7 C, about 20 to about 30 Cr, about 20 to about 30 Ni, about 0.5 to about 1 Mn, about 0.6 to about 2 Si, about 0.05 to about 1 Nb, about 0.05 to about 1 W, about 0.05 to about 1.0 Mo, balance Fe, the steel being essentially free of Ti and Co, the steel characterized by at least one microstructural component selected from the group consisting of MC, M.sub.23C.sub.6, and M(C, N).

  5. Cast, heat-resistant austenitic stainless steels having reduced alloying element content

    DOEpatents

    Muralidharan, Govindarajan [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Maziasz, Philip J [Oak Ridge, TN; Pankiw, Roman I [Greensburg, PA

    2011-08-23

    A cast, austenitic steel composed essentially of, expressed in weight percent of the total composition, about 0.4 to about 0.7 C, about 20 to about 30 Cr, about 20 to about 30 Ni, about 0.5 to about 1 Mn, about 0.6 to about 2 Si, about 0.05 to about 1 Nb, about 0.05 to about 1 W, about 0.05 to about 1.0 Mo, balance Fe, the steel being essentially free of Ti and Co, the steel characterized by at least one microstructural component selected from the group consisting of MC, M.sub.23C.sub.6, and M(C, N).

  6. Improvements in Low-Frequency, Ultrasonic Phased-Array Evaluation for Thick Section Cast Austenitic Stainless Steel Piping Components

    SciTech Connect

    Anderson, Michael T.; Crawford, Susan L.; Diaz, Aaron A.; Moran, Traci L.

    2010-12-01

    Research is being conducted for the U.S. Nuclear Regulatory Commission (NRC) at the Pacific Northwest National Laboratory (PNNL) to assess the effectiveness and reliability of advanced nondestructive examination (NDE) methods for the inspection of light water reactor (LWR) components. A primary objective of this work is to evaluate various NDE methods to assess their ability to detect, localize, and size cracks in coarse-grained steel components. This particular study focused on the evaluation of custom-designed, low-frequency (500 kHz) phased-array (PA) probes for examining welds in thick-section cast austenitic stainless steel (CASS) piping. In addition, research was conducted to observe ultrasonic sound field propagation effects from known coarse-grained microstructures found in parent CASS material. The study was conducted on a variety of thick-wall, coarse-grained CASS specimens that were previously inspected by an older generation 500-kHz PA-UT probe and acquisition instrument configuration. This comparative study describes the impact of the new PA probe design on flaw detection and sizing in a low signal-to-noise environment. The set of Pressurized Water Reactor Owners Group (PWROG) CASS specimens examined in this study are greater than 50.8-mm (2.0-in.) thick with documented flaws and microstructures. These specimens are on loan to PNNL from the Electric Power Research Institute (EPRI) NDE Center in Charlotte, North Carolina. The flaws contained within these specimens are thermal fatigue cracks (TFC) or mechanical fatigue cracks (MFC) and range from 13% to 42% in through-wall extent. In addition, ultrasonic signal continuity was evaluated on two CASS parent material ring sections by examining the edge-of-pipe response (corner geometry) for regions of signal loss.

  7. Task 1 Final Report, Theoretical/Mathematical Modeling of Ultrasonic Wave Propagation in Anisotropic Polycrystalline Stainless Steels

    SciTech Connect

    Ahmed, Salahuddin; Anderson, Michael T.

    2009-04-20

    One of the tasks of the U.S. Nuclear Regulatory Commission-sponsored project titled "Reliability of Nondestructive Examination (NDE) for Nuclear Power Plant (NPP) Inservice Examination (ISI)" is to provide collaborative assistance to Commissariat à l’Energie Atomique (CEA) in France through theoretical predictions of ultrasonic scattering by grains of cast stainless steels (CASS) components. More specifically, a mathematical treatment of ultrasonic scattering in media having duplex micro¬structure is sought because cast stainless steel components often contains larger-scale macrograins that are composed of sub-grains/colonies. In this report, we present formal mathematical theories for ultrasonic wave propagation in polycrystalline aggregates having both simple (composed of grains only) and complex microstructures (having macrograins and sub-grains/colonies). Computations based on these theories are then carried out for ultrasonic backscatter power, attenuation due to scattering, and phase velocity dispersions. Specifically, numerical results are presented for backscatter coefficient for plane longitudinal wave propagating in duplex steel containing macrograins and colonies. Furthermore, the expected propagation characteristics (attenuation coefficient and phase velocity) are computed and described in this report for plane longitudinal waves propagating in (1) steels composed of randomly oriented grains, (2) [001] aligned grains encountered in austenitic stainless steel welds and casts, and (3) duplex steels.

  8. Molecular characterization of natural biofilms from household taps with different materials: PVC, stainless steel, and cast iron in drinking water distribution system.

    PubMed

    Lin, Wenfang; Yu, Zhisheng; Chen, Xi; Liu, Ruyin; Zhang, Hongxun

    2013-09-01

    Microorganism in drinking water distribution system may colonize in biofilms. Bacterial 16S rRNA gene diversities were analyzed in both water and biofilms grown on taps with three different materials (polyvinyl chloride (PVC), stainless steel, and cast iron) from a local drinking water distribution system. In total, five clone libraries (440 sequences) were obtained. The taxonomic composition of the microbial communities was found to be dominated by members of Proteobacteria (65.9-98.9 %), broadly distributed among the classes Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria. Other bacterial groups included Firmicutes, Acidobacteria, Bacteroidetes, Cyanobacteria, and Deinococcus-Thermus. Moreover, a small proportion of unclassified bacteria (3.5-10.6 %) were also found. This investigation revealed that the bacterial communities in biofilms appeared much more diversified than expected and more care should be taken to the taps with high bacterial diversity. Also, regular monitor of outflow water would be useful as potentially pathogenic bacteria were detected. In addition, microbial richness and diversity in taps ranked in the order as: PVC < stainless steel < cast iron. All the results interpreted that PVC would be a potentially suitable material for use as tap component in drinking water distribution system.

  9. Development of Cast Alumina-forming Austenitic Stainless Steel Alloys for use in High Temperature Process Environments

    SciTech Connect

    Muralidharan, Govindarajan; Yamamoto, Yukinori; Brady, Michael P; Pint, Bruce A; Pankiw, Roman; Voke, Don

    2015-01-01

    There is significant interest in the development of alumina-forming, creep resistant alloys for use in various industrial process environments. It is expected that these alloys can be fabricated into components for use in these environments through centrifugal casting and welding. Based on the successful earlier studies on the development of wrought versions of Alumina-Forming Austenitic (AFA) alloys, new alloy compositions have been developed for cast products. These alloys achieve good high-temperature oxidation resistance due to the formation of protective Al2O3 scales while multiple second-phase precipitation strengthening contributes to excellent creep resistance. This work will summarize the results on the development and properties of a centrifugally cast AFA alloy. This paper highlights the strength, oxidation resistance in air and water vapor containing environments, and creep properties in the as-cast condition over the temperature range of 750°C to 900°C in a centrifugally cast heat. Preliminary results for a laboratory cast AFA composition with good oxidation resistance at 1100°C are also presented.

  10. Technical Letter Report Assessment of Ultrasonic Phased Array Testing for Cast Austenitic Stainless Steel Pressurizer Surge Line Piping Welds and Thick Section Primary System Cast Piping Welds JCN N6398, Task 2A

    SciTech Connect

    Diaz, Aaron A.; Denslow, Kayte M.; Cinson, Anthony D.; Morra, Marino; Crawford, Susan L.; Prowant, Matthew S.; Cumblidge, Stephen E.; Anderson, Michael T.

    2008-07-21

    Research is being conducted for the NRC at PNNL to assess the effectiveness and reliability of advanced NDE methods for the inspection of LWR components. The scope of this research encompasses primary system pressure boundary materials including cast austenitic stainless steels (CASS), dissimilar metal welds (DMWs), piping with corrosion-resistant cladding, weld overlays, and far-side examinations of austenitic piping welds. A primary objective of this work is to evaluate various NDE methods to assess their ability to detect, localize, and size cracks in coarse-grained steel components. This interim technical letter report (TLR) provides a synopsis of recent investigations at PNNL aimed at evaluating the capabilities of phased-array (PA) ultrasonic testing (UT) methods as applied to the inspection of CASS welds in nuclear reactor piping. A description of progress, recent developments and interim results are provided.

  11. TEM (transmission electron microscopy), APFIM (atom-probe field ion microscopy), and SANS (small-angle neutron scattering) examination of aged duplex stainless steel components from some decommissioned reactors

    SciTech Connect

    Chung, H.M.; Chopra, O.K.

    1987-12-01

    The present investigation indicates that the primary embrittlement processes of the CF-8 grade cast stainless steel components during extended reactor service are spinodal decomposition of the ferrite phase and M/sub 23/C/sub 6/ carbide precipitation on the austenite-ferrite boundaries. The ferrite hardness measured for the Shippingport reactor valves appears to reflect the different extent of spinodal decomposition among the different valves which contain slightly different Cr contents. G-phase precipitation was minimal compared to that during accelerated aging of CF-8 steel in the laboratory (i.e., near 400/degree/C). This indicates that the activation energy may be strongly influenced by the synergism among the G-phase precipitation, carbide formation, and spinodal decomposition. 13 refs., 2 figs.

  12. Effect of the Solution Annealing and Chemical Passivation Followed by Aging on the Corrosion of Shell Mold Cast CF8 Stainless Steel

    NASA Astrophysics Data System (ADS)

    Kim, Kuk-Jin; Ju, Heongkyu; Moon, Young-Dae; Hong, Jun Ho; Pak, Sung Joon

    2016-10-01

    The effects of solution annealing and passivation of shell mold cast CF8 stainless steels on Elbow pipe fittings with 2-month room temperature aging have been studied using a corrosion technique. The resistance of corrosion increased with 2-month room temperature aging combined with solid solution annealing and chemical passivation. The mode of corrosion was deeply related to the δ-ferrite content, permeability, and passivation. The corrosion probability decreased as both the δ-ferrite content and the permeability decreased. Therefore, it is considered that δ-ferrite content and passive film of Cr2O3 play an important role in corrosion resistance of CF8 Elbow pipe fittings due to the long-term aging with solid solution annealing and chemical passivation. This result shows that the corrosion resistance of CF8 fittings can be enhanced by the solid solution annealing and chemical passivation. Decreased ferrite phases and permeability improve IGC resistance in CF8 steel.

  13. Effects of long-term thermal aging on the stress corrosion cracking behavior of cast austenitic stainless steels in simulated PWR primary water

    NASA Astrophysics Data System (ADS)

    Li, Shilei; Wang, Yanli; Wang, Hui; Xin, Changsheng; Wang, Xitao

    2016-02-01

    The stress corrosion cracking (SCC) behavior of cast austenitic stainless steels of unaged and thermally aged at 400 °C for as long as 20,000 h were studied by using a slow strain rate testing (SSRT) system. Spinodal decomposition in ferrite during thermal aging leads to hardening in ferrite and embrittlement of the SSRT specimen. Plastic deformation and thermal aging degree have a great influence on the oxidation rate of the studied material in simulated PWR primary water environments. In the SCC regions of the aged SSRT specimen, the surface cracks, formed by the brittle fracture of ferrite phases, are the possible locations for SCC. In the non-SCC regions, brittle fracture of ferrite phases also occurs because of the effect of thermal aging embrittlement.

  14. Effect of the Solution Annealing and Chemical Passivation Followed by Aging on the Corrosion of Shell Mold Cast CF8 Stainless Steel

    NASA Astrophysics Data System (ADS)

    Kim, Kuk-Jin; Ju, Heongkyu; Moon, Young-Dae; Hong, Jun Ho; Pak, Sung Joon

    2016-07-01

    The effects of solution annealing and passivation of shell mold cast CF8 stainless steels on Elbow pipe fittings with 2-month room temperature aging have been studied using a corrosion technique. The resistance of corrosion increased with 2-month room temperature aging combined with solid solution annealing and chemical passivation. The mode of corrosion was deeply related to the δ-ferrite content, permeability, and passivation. The corrosion probability decreased as both the δ-ferrite content and the permeability decreased. Therefore, it is considered that δ-ferrite content and passive film of Cr2O3 play an important role in corrosion resistance of CF8 Elbow pipe fittings due to the long-term aging with solid solution annealing and chemical passivation. This result shows that the corrosion resistance of CF8 fittings can be enhanced by the solid solution annealing and chemical passivation. Decreased ferrite phases and permeability improve IGC resistance in CF8 steel.

  15. Stainless Steel Permeability

    SciTech Connect

    Buchenauer, Dean A.; Karnesky, Richard A.

    2015-09-01

    An understanding of the behavior of hydrogen isotopes in materials is critical to predicting tritium transport in structural metals (at high pressure), estimating tritium losses during production (fission environment), and predicting in-vessel inventory for future fusion devices (plasma driven permeation). Current models often assume equilibrium diffusivity and solubility for a class of materials (e.g. stainless steels or aluminum alloys), neglecting trapping effects or, at best, considering a single population of trapping sites. Permeation and trapping studies of the particular castings and forgings enable greater confidence and reduced margins in the models. For FY15, we have continued our investigation of the role of ferrite in permeation for steels of interest to GTS, through measurements of the duplex steel 2507. We also initiated an investigation of the permeability in work hardened materials, to follow up on earlier observations of unusual permeability in a particular region of 304L forgings. Samples were prepared and characterized for ferrite content and coated with palladium to prevent oxidation. Issues with the poor reproducibility of measurements at low permeability were overcome, although the techniques in use are tedious. Funding through TPBAR and GTS were secured for a research grade quadrupole mass spectrometer (QMS) and replacement turbo pumps, which should improve the fidelity and throughput of measurements in FY16.

  16. Oxidation of Slurry Aluminide Coatings on Cast Stainless Steel Alloy CF8C-Plus at 800oC in Water Vapor

    SciTech Connect

    Haynes, James A; Armstrong, Beth L; Dryepondt, Sebastien N; Kumar, Deepak; Zhang, Ying

    2013-01-01

    A new, cast austenitic stainless steel, CF8C-Plus, has been developed for a wide range of high temperature applications, including diesel exhaust components, turbine casings and turbocharger housings. CF8C-Plus offers significant improvements in creep rupture life and creep rupture strength over standard CF8C steel. However, at higher temperatures and in more aggressive environments, such as those containing significant water vapor, an oxidation-resistant protective coating will be necessary. The oxidation behavior of alloys CF8C and CF8C-Plus with various aluminide coatings were compared at 800oC in air plus 10 vol% water vapor. Due to their affordability, slurry aluminides were the primary coating system of interest, although chemical vapor deposition (CVD) and pack cementation coatings were also compared. Additionally, a preliminary study of the low cycle fatigue behavior of aluminized CF8C-Plus was conducted at 800oC. Each type of coating provided substantial improvements in oxidation behavior, with simple slurry aluminides showing very good oxidation resistance after 4,000 h testing in water vapor. Preliminary low cycle fatigue results indicated that thicker aluminide coatings degraded high temperature fatigue properties of CF8C-Plus, whereas thinner coatings did not. Results suggest that appropriately designed slurry aluminide coatings are a viable option for economical, long-term oxidation protection of austenitic stainless steels in water vapor.

  17. Ultrasonic Phased Array Evaluations Of Implanted And In-Situ Grown Flaws In Cast Austenitic Stainless Steel Pressurizer Surge Line Piping

    SciTech Connect

    Crawford, Susan L.; Cinson, Anthony D.; Moran, Traci L.; Prowant, Matthew S.; Diaz, Aaron A.; Anderson, Michael T.

    2011-07-31

    A set of circumferentially oriented thermal fatigue cracks (TFCs) were implanted into three cast austenitic stainless steel (CASS) pressurizer (PZR) surge-line specimen welds (pipe-to-elbow configuration) that were salvaged from a U.S. commercial nuclear power plant that had not been operated. Thus, these welds were fabricated using vintage CASS materials that were formed in the 1970s. Additionally, in-situ grown TFCs were placed in the adjacent CASS base material of one of these specimens. Ultrasonic phased-array responses from both types of flaws (implanted and in-situ grown) were analyzed for detection and characterization based on sizing and signal-to-noise determination. Multiple probes were employed covering the 0.8 to 2.0 MHz frequency range. To further validate the Pacific Northwest National Laboratory (PNNL) findings, an independent in-service inspection (ISI) supplier evaluated the flaws with their American Society of Mechanical Engineers (ASME) Code, Section XI, Appendix VIII-qualified procedure. The results obtained by PNNL personnel compared favorably to the ISI supplier results. All examined flaws were detected and sized within the ASME Code-allowable limits.

  18. Hybrid Laser-Arc Welding of 10-mm-Thick Cast Martensitic Stainless Steel CA6NM: As-Welded Microstructure and Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Mirakhorli, Fatemeh; Cao, Xinjin; Pham, Xuan-Tan; Wanjara, Priti; Fihey, Jean-Luc

    2016-07-01

    Cast CA6NM martensitic stainless steel plates, 10 mm in thickness, were welded using hybrid laser-arc welding. The effect of different welding speeds on the as-welded joint integrity was characterized in terms of the weld bead geometry, defects, microstructure, hardness, ultimate tensile strength, and impact energy. Significant defects such as porosity, root humping, underfill, and excessive penetration were observed at a low welding speed (0.5 m/min). However, the underfill depth and excessive penetration in the joints manufactured at welding speeds above 0.75 m/min met the specifications of ISO 12932. Characterization of the as-welded microstructure revealed untempered martensite and residual delta ferrite dispersed at prior-austenite grain boundaries in the fusion zone. In addition, four different heat-affected zones in the weldments were differentiated through hardness mapping and inference from the Fe-Cr-Ni ternary phase diagram. The tensile fracture occurred in the base metal for all the samples and fractographic analysis showed that the crack path is within the martensite matrix, along primary delta ferrite-martensite interfaces and within the primary delta ferrite. Additionally, Charpy impact testing demonstrated slightly higher fracture energy values and deeper dimples on the fracture surface of the welds manufactured at higher welding speeds due to grain refinement and/or lower porosity.

  19. Effect of Bonding Temperature on Phase Transformation of Diffusion-Bonded Joints of Duplex Stainless Steel and Ti-6Al-4V Using Nickel and Copper as Composite Intermediate Metals

    NASA Astrophysics Data System (ADS)

    Kundu, Sukumar; Thirunavukarasu, Gopinath; Chatterjee, Subrata; Mishra, Brajendra

    2015-12-01

    In the present study, the effect of bonding temperature on phase transformation of diffusion-bonded joints of duplex stainless steel (DSS) and Ti-6Al-4V (Ti64) using simultaneously both nickel (Ni) and copper (Cu) interlayers was investigated in the temperature range of 1148 K to 1223 K (875 °C to 950 °C) insteps of 25 K (25 °C) for 60 minutes under 4 MPa uniaxial pressure in vacuum. Interfaces were characterized by scanning electron microscopy and interdiffusion of the chemical species across the diffusion interfaces were witnessed by electron probe microanalysis. At 1148 K (875 °C), layer-wise Cu4Ti, Cu2Ti, Cu4Ti3, CuTi, and CuTi2 phases were observed at the Cu-Ti64 interface; however, DSS-Ni and Ni-Cu interfaces were free from any intermetallic. At 1173 K and 1198 K (900 °C and 925 °C), Cu interlayer could not restrict the diffusion of atoms from Ti64 to Ni, and vice versa; and Ni-Ti-based intermetallics were formed at the Ni-Cu interface and throughout the Cu zone as well; however, at 1223 K (950 °C), both Ni and Cu interlayers could not inhibit the diffusion of atoms from Ti64 to DSS, and vice versa. The maximum shear strength of ~377 MPa was obtained for the diffusion couple processed at 1148 K (875 °C) and strength of the bonded joints gradually decreased with the increasing bonding temperature due to the widening of brittle intermetallics at the diffusion zone. Fracture path indicated that failure took place through the Cu4Ti intermetallic at the Cu-Ti64 interface when bonding was processed at 1148 K (875 °C). When bonding was processed at 1173 K and 1198 K (900 °C and 925 °C), fracture took place through the Ni3Ti intermetallic at the Ni-(Ni + Cu + Ti64 diffusion reaction) interface; however, at 1223 K (950 °C), fracture morphology indicated the brittle nature and the fracture took place apparently through the σ phase at the DSS-(DSS + Ni + Cu + Ti64 diffusion reaction) interface.

  20. Effects of phosphate addition on biofilm bacterial communities and water quality in annular reactors equipped with stainless steel and ductile cast iron pipes.

    PubMed

    Jang, Hyun-Jung; Choi, Young-June; Ro, Hee-Myong; Ka, Jong-Ok

    2012-02-01

    The impact of orthophosphate addition on biofilm formation and water quality was studied in corrosion-resistant stainless steel (STS) pipe and corrosion-susceptible ductile cast iron (DCI) pipe using cultivation and culture-independent approaches. Sample coupons of DCI pipe and STS pipe were installed in annular reactors, which were operated for 9 months under hydraulic conditions similar to a domestic plumbing system. Addition of 5 mg/L of phosphate to the plumbing systems, under low residual chlorine conditions, promoted a more significant growth of biofilm and led to a greater rate reduction of disinfection by-products in DCI pipe than in STS pipe. While the level of THMs (trihalomethanes) increased under conditions of low biofilm concentration, the levels of HAAs (halo acetic acids) and CH (chloral hydrate) decreased in all cases in proportion to the amount of biofilm. It was also observed that chloroform, the main species of THM, was not readily decomposed biologically and decomposition was not proportional to the biofilm concentration; however, it was easily biodegraded after the addition of phosphate. Analysis of the 16S rDNA sequences of 102 biofilm isolates revealed that Proteobacteria (50%) was the most frequently detected phylum, followed by Firmicutes (10%) and Actinobacteria (2%), with 37% of the bacteria unclassified. Bradyrhizobium was the dominant genus on corroded DCI pipe, while Sphingomonas was predominant on non-corroded STS pipe. Methylobacterium and Afipia were detected only in the reactor without added phosphate. PCR-DGGE analysis showed that the diversity of species in biofilm tended to increase when phosphate was added regardless of the pipe material, indicating that phosphate addition upset the biological stability in the plumbing systems.

  1. Effects of phosphate addition on biofilm bacterial communities and water quality in annular reactors equipped with stainless steel and ductile cast iron pipes.

    PubMed

    Jang, Hyun-Jung; Choi, Young-June; Ro, Hee-Myong; Ka, Jong-Ok

    2012-02-01

    The impact of orthophosphate addition on biofilm formation and water quality was studied in corrosion-resistant stainless steel (STS) pipe and corrosion-susceptible ductile cast iron (DCI) pipe using cultivation and culture-independent approaches. Sample coupons of DCI pipe and STS pipe were installed in annular reactors, which were operated for 9 months under hydraulic conditions similar to a domestic plumbing system. Addition of 5 mg/L of phosphate to the plumbing systems, under low residual chlorine conditions, promoted a more significant growth of biofilm and led to a greater rate reduction of disinfection by-products in DCI pipe than in STS pipe. While the level of THMs (trihalomethanes) increased under conditions of low biofilm concentration, the levels of HAAs (halo acetic acids) and CH (chloral hydrate) decreased in all cases in proportion to the amount of biofilm. It was also observed that chloroform, the main species of THM, was not readily decomposed biologically and decomposition was not proportional to the biofilm concentration; however, it was easily biodegraded after the addition of phosphate. Analysis of the 16S rDNA sequences of 102 biofilm isolates revealed that Proteobacteria (50%) was the most frequently detected phylum, followed by Firmicutes (10%) and Actinobacteria (2%), with 37% of the bacteria unclassified. Bradyrhizobium was the dominant genus on corroded DCI pipe, while Sphingomonas was predominant on non-corroded STS pipe. Methylobacterium and Afipia were detected only in the reactor without added phosphate. PCR-DGGE analysis showed that the diversity of species in biofilm tended to increase when phosphate was added regardless of the pipe material, indicating that phosphate addition upset the biological stability in the plumbing systems. PMID:22367933

  2. Technical Letter Report Assessment of Ultrasonic Phased Array Inspection Method for Welds in Cast Austenitic Stainless Steel Pressurizer Surge Line Piping JCN N6398, Task 1B

    SciTech Connect

    Diaz, Aaron A.; Cinson, Anthony D.; Crawford, Susan L.; Mathews, Royce; Moran, Traci L.; Anderson, Michael T.

    2009-07-28

    Research is being conducted for the U.S. Nuclear Regulatory Commission (NRC) at the Pacific Northwest National Laboratory (PNNL) to assess the effectiveness and reliability of advanced nondestructive examination (NDE) methods for the inspection of light water reactor components. The scope of this research encompasses primary system pressure boundary materials including cast austenitic stainless steels (CASS); dissimilar metal welds; piping with corrosion-resistant cladding; weld overlays, inlays and onlays; and far-side examinations of austenitic piping welds. A primary objective of this work is to evaluate various NDE methods to assess their ability to detect, localize, and size cracks in coarse-grained steel components. In this effort, PNNL supports cooperation with Commissariat à l’Energie Atomique (CEA) to assess reliable inspection of CASS materials. The NRC Project Manager has established a cooperative effort with the Institut de Radioprotection et de Surete Nucleaire (IRSN). CEA, under funding from IRSN, are supporting collaborative efforts with the NRC and PNNL. Regarding its work on the NDE of materials, CEA is providing its modeling software (CIVA) in exchange for PNNL offering expertise and data related to phased-array detection and sizing, acoustic attenuation, and back scattering on CASS materials. This collaboration benefits the NRC because CEA performs research and development on CASS for Électricité de France (EdF). This technical letter report provides a summary of a technical evaluation aimed at assessing the capabilities of phased-array (PA) ultrasonic testing (UT) methods as applied to the inspection of welds in CASS pressurizer (PZR) surge line nuclear reactor piping. A set of thermal fatigue cracks (TFCs) was implanted into three CASS PZR surge-line specimens (pipe-to-elbow welds) that were fabricated using vintage CASS materials formed in the 1970s, and flaw responses from these cracks were used to evaluate detection and sizing

  3. Welding Metallurgy and Weldability of Stainless Steels

    NASA Astrophysics Data System (ADS)

    Lippold, John C.; Kotecki, Damian J.

    2005-03-01

    Welding Metallurgy and Weldability of Stainless Steels, the first book in over twenty years to address welding metallurgy and weldability issues associated with stainless steel, offers the most up-to-date and comprehensive treatment of these topics currently available. The authors emphasize fundamental metallurgical principles governing microstructure evolution and property development of stainless steels, including martensistic, ferric, austenitic, duplex, and precipitation hardening grades. They present a logical and well-organized look at the history, evolution, and primary uses of each stainless steel, including detailed descriptions of the associated weldability issues.

  4. Urinary casts

    MedlinePlus

    ... the urine; Fatty casts; Red blood cell casts; White blood cell casts ... with advanced kidney disease and chronic kidney failure . White blood cell (WBC) casts are more common with acute kidney ...

  5. Duplex tab exhaust nozzle

    NASA Technical Reports Server (NTRS)

    Gutmark, Ephraim Jeff (Inventor); Martens, Steven (nmn) (Inventor)

    2012-01-01

    An exhaust nozzle includes a conical duct terminating in an annular outlet. A row of vortex generating duplex tabs are mounted in the outlet. The tabs have compound radial and circumferential aft inclination inside the outlet for generating streamwise vortices for attenuating exhaust noise while reducing performance loss.

  6. Post-weld Tempered Microstructure and Mechanical Properties of Hybrid Laser-Arc Welded Cast Martensitic Stainless Steel CA6NM

    NASA Astrophysics Data System (ADS)

    Mirakhorli, Fatemeh; Cao, Xinjin; Pham, Xuan-Tan; Wanjara, Priti; Fihey, Jean-Luc

    2016-01-01

    Manufacturing of hydroelectric turbine components involves the assembly of thick-walled stainless steels using conventional multi-pass arc welding processes. By contrast, hybrid laser-arc welding may be an attractive process for assembly of such materials to realize deeper penetration depths, higher production rates, narrower fusion, and heat-affected zones, and lower distortion. In the present work, single-pass hybrid laser-arc welding of 10-mm thick CA6NM, a low carbon martensitic stainless steel, was carried out in the butt joint configuration using a continuous wave fiber laser at its maximum power of 5.2 kW over welding speeds ranging from 0.75 to 1.2 m/minute. The microstructures across the weldment were characterized after post-weld tempering at 873 K (600 °C) for 1 hour. From microscopic examinations, the fusion zone was observed to mainly consist of tempered lath martensite and some residual delta-ferrite. The mechanical properties were evaluated in the post-weld tempered condition and correlated to the microstructures and defects. The ultimate tensile strength and Charpy impact energy values of the fully penetrated welds in the tempered condition were acceptable according to ASTM, ASME, and industrial specifications, which bodes well for the introduction of hybrid laser-arc welding technology for the manufacturing of next generation hydroelectric turbine components.

  7. On the stress corrosion cracking of lean duplex steel in chloride environment

    NASA Astrophysics Data System (ADS)

    Tayyaba, Qanita; Farooq, Hina; Shahid, Muhammad; Jadoon, Ammer Khan; Shahzad, M.; Qureshi, A. H.

    2014-06-01

    Duplex stainless steel having attractive combination of austenitic and ferritic properties is being used in industry such as petrochemical, pulp and paper mills. In this study, the corrosion and stress corrosion behavior of duplex stainless steel in 3.5% sodium chloride environment was investigated by weight loss measurements, electrochemical DC testing and slow strain rate test (SSRT). Weight loss data showed no significant corrosion after 1700 hours. Electrochemical polarization test in 3.5% NaCl solution exhibited a uniform corrosion rate of 0.008 mpy (calculated using Tafel analysis) showing passivity in the range of 735-950 mV. A comparison of the slow strain rate test in 3.5% NaCl solution with air shows almost a similar stress strain curve for duplex stainless steel. In comparison, the stress strain curves for 0.15% carbon steel show a loss of about 25% tensile elongation for the same comparison. The excellent corrosion and especially resistance to localized corrosion (pitting) is responsible for no loss of ductility in duplex stainless steel.

  8. Improvements in 500-kHz Ultrasonic Phased-Array Probe Designs for Evaluation of Thick Section Cast Austenitic Stainless Steel Piping Welds

    SciTech Connect

    Crawford, Susan L.; Cinson, Anthony D.; Moran, Traci L.; Anderson, Michael T.; Diaz, Aaron A.

    2011-02-01

    PNNL has been studying and performing confirmatory research on the inspection of piping welds in coarse-grained steels for over 30 years. More recent efforts have been the application of low frequency phased array technology to this difficult to inspect material. The evolution of 500 kHz PA probes and the associated electronics and scanning protocol are documented in this report. The basis for the probe comparisons are responses from one mechanical fatigue crack and two thermal fatigue cracks in large-bore cast mockup specimens on loan from the Electric Power Research Institution. One of the most significant improvements was seen in the use of piezo-composite elements in the later two probes instead of the piezo-ceramic material used in the prototype array. This allowed a reduction in system gain of 30 dB and greatly reduced electronic noise. The latest probe had as much as a 5 dB increase in signal to noise, adding to its flaw discrimination capability. The system electronics for the latest probe were fully optimized for a 500 kHz center frequency, however significant improvements were not observed in the center frequency of the flaw responses. With improved scanner capabilities, smaller step sizes were used, allowing both line and raster data improvements to be made with the latest probe. The small step sizes produce high resolution images that improve flaw discrimination and, along with the increased signal-to-noise ratio inherent in the latest probe design, enhanced detection of the upper regions of the flaw make depth sizing more plausible. Finally, the physical sizes of the probes were progressively decreased allowing better access to the area of interest on specimens with weld crowns, and the latest probe was designed with non-integral wedges providing flexibility in focusing on different specimen geometries.

  9. Microstructure and Elemental Distribution in a Cast Austenitic Steel

    SciTech Connect

    Kenik, Edward A; Busby, Jeremy T; Hoelzer, David T; Rowcliffe, Arthur Frederick; Vitek, John Michael

    2007-01-01

    Casting of austenitic stainless steels offers the possibility of directly producing large and/or complex structures, such as the first wall shield module or the diverter cassette for the International Tokomak Experimental Reactor. However, the resulting mechanical properties and the corrosion resistance of such cast components can be inferior compared to conventionally forged components because of the larger grain size, lower dislocation density and extensive segregation inherent in the cast material. This study examines the microstructural and compositional heterogeneities of a large casting of 316N stainless steel, as well as the possibility of improving the homogeneity and mechanical properties of such a cast material.

  10. Researches upon cavitation erosion behavior of some duplex steels

    NASA Astrophysics Data System (ADS)

    Bordeasu, I.; Popoviciu, M. O.; Mitelea, I.; Micu, L. M.; Bordeasu, C.; Ghera, C.; Iosif, A.

    2016-02-01

    This paper presents the cavitation erosion behavior of two stainless steels having a duplex structure formed by austenite and ferrite. The conclusions were obtained by using both the cavitation erosion characteristic curves and the pictures of the eroded surfaces obtained with performing optic microscopes. The researches were focused upon the optimal correlation between the cavitation erosion resistance and the rate of the two structural constituents. The tests were done with T2 facility, with ceramic crystals, which integrally respects the ASTM G32-2010 Standard. The obtained results present the cumulative effect upon cavitation erosion of the chemical composition, mechanical properties and the structural constituents. The results of the researches are of importance for the specialists which establishes the composition of the stainless steels used for manufacturing hydraulic machineries or other devices subjected to cavitation erosion.

  11. Austenitic stainless steels for cryogenic service

    SciTech Connect

    Dalder, E.N.C.; Juhas, M.C.

    1985-09-19

    Presently available information on austenitic Fe-Cr-Ni stainless steel plate, welds, and castings for service below 77 K are reviewed with the intent (1) of developing systematic relationships between mechanical properties, composition, microstructure, and processing, and (2) of assessing the adequacy of these data bases in the design, fabrication, and operation of engineering systems at 4 K.

  12. PNA beacons for duplex DNA.

    PubMed

    Kuhn, H; Demidov, V V; Gildea, B D; Fiandaca, M J; Coull, J C; Frank-Kamenetskii, M D

    2001-08-01

    We report here on the hybridization of peptide nucleic acid (PNA)-based molecular beacons (MB) directly to duplex DNA sites locally exposed by PNA openers. Two stemless PNA beacons were tested, both featuring the same recognition sequence and fluorophore-quencher pair (Fluorescein and DABCYL, respectively) but differing in arrangement of these groups and net electrostatic charge. It was found that one PNA beacon rapidly hybridized, with the aid of openers, to its complementary target within duplex DNA at ambient conditions via formation of a PD-like loop. In contrast, the other PNA beacon bound more slowly to preopened duplex DNA target and only at elevated temperatures, although it readily hybridized to single-stranded (ss) DNA target. Besides a higher selectivity of hybridization provided by site-specific PNA openers, we expect this approach to be very useful in those MB applications when denaturation of the duplex DNA analytes is unfavorable or undesirable. Furthermore, we show that PNA beacons are advantageous over DNA beacons for analyzing unpurified/nondeproteinized DNA samples. This feature of PNA beacons and our innovative hybridization strategy may find applications in emerging fluorescent DNA diagnostics.

  13. Superplastic forming of stainless steel automotive components

    SciTech Connect

    Bridges, B.; Elmer, J.; Carol, L.

    1997-02-06

    Exhaust emission standards are governmentally controlled standards, which are increasingly stringent, forcing alternate strategies to meet these standards. One approach to improve the efficiency of the exhaust emission equipment is to decrease the time required to get the catalytic converter to optimum operating temperature. To accomplish this, automotive manufacturers are using double wall stainless steel exhaust manifolds to reduce heat loss of the exhaust gases to the converter. The current method to manufacture double wall stainless steel exhaust components is to use a low-cost alloy with good forming properties and extensively form, cut, assemble, and weld the pieces. Superplastic forming (SPF) technology along with alloy improvements has potential at making this process more cost effective. Lockheed Martin Energy Systems (LMES), Lawrence Livermore National Laboratory (LLNL) and USCAR Low Emission Partnership (LEP) worked under a Cooperative Research And Development Agreement (CRADA) to evaluate material properties, SPF behavior, and welding behavior of duplex stainless steel alloy for automotive component manufacturing. Battelle Pacific Northwest National Laboratory (PNNL) has a separate CRADA with the LEP to use SPF technology to manufacture a double wall stainless steel exhaust component. As a team these CRADAs developed and demonstrated a technical plan to accomplish making double wall stainless steel exhaust manifolds.

  14. Properties of modified 9Cr-1Mo cast steel

    SciTech Connect

    Zucco, J.A.; Canonico, D.A.

    1996-09-01

    This report describes the development and testing of a cast version of the popular ASME P-91 ferritic stainless steel. ASME and ASTM have approved its use in pressure vessels and boilers. The allowable strength level of the cast material is slightly lower than that of P- 91 wrought steel. The report also describes shop and field welding procedures developed for the cast steel. Figs, tabs.

  15. Superstructure of linear duplex DNA.

    PubMed Central

    Vollenweider, H J; Koller, T; Parello, J; Sogo, J M

    1976-01-01

    The superstructure of a covalently closed circular DNA (of bacteriophage PM 2) was compared by electron microscopy with that of a linear duplex DNA (of bacteriophage T7) when ionic strength and benzyldimethylalkylammonium chloride concentration were varied. In parallel studies the sedimentation behavior of these DNAs was studied by analytical ultracentrifugation, but for technical reasons these had to be without benzyldimethylalkylammonium chloride. By combining the information from the two methods one has to conclude that with increasing ionic strength the linear duplex T7 DNA spontaneously forms a structure similar to that of the superhelical structure of closed circular PM 2 DNA. The superstructure is destroyed under premelting conditions and in the presence of an excess of ethidium bromide. Images PMID:1069302

  16. Pigmented casts.

    PubMed

    Miteva, Mariya; Romanelli, Paolo; Tosti, Antonella

    2014-01-01

    Pigmented casts have been reported with variable frequency in scalp biopsies from alopecia areata, trichotillomania, chemotherapy-induced alopecia and postoperative (pressure induced) alopecia. Their presence and morphology in other scalp disorders has not been described. The authors assessed for the presence and morphology of pigmented casts in 308 transversely bisected scalp biopsies from nonscarring and scarring alopecia, referred to the Department of Dermatology, University of Miami within a year. The pigmented casts were present in 21 of 29 cases of alopecia areata (72%), 7 of 7 cases of trichotillomania (100%), 1 case of friction alopecia, 4 of 28 cases of central centrifugal cicatricial alopecia (14%), and 4 of 4 cases of dissecting cellulitis (100%). They did not show any distinguishing features except for the morphology in trichotillomania, which included twisted, linear (zip), and "button"-like pigment aggregation. The linear arrangement was found also in friction alopecia and dissecting cellulitis. Pigmented casts in the hair canals of miniaturized/vellus hairs was a clue to alopecia areata. Pigmented casts can be observed in biopsies of different hair disorders, but they are not specific for the diagnosis. Horizontal sections allow to better assess their morphology and the follicular level of presence of pigmented casts, which in the context of the other follicular findings may be a clue to the diagnosis. PMID:23823025

  17. Processing of IN-718 Lattice Block Castings

    NASA Technical Reports Server (NTRS)

    Hebsur, Mohan G.

    2002-01-01

    Recently a low cost casting method known as lattice block casting has been developed by JAM Corporation, Wilmington, Massachusetts for engineering materials such as aluminum and stainless steels that has shown to provide very high stiffness and strength with only a fraction of density of the alloy. NASA Glenn Research Center has initiated research to investigate lattice block castings of high temperature Ni-base superalloys such as the model system Inconel-718 (IN-718) for lightweight nozzle applications. Although difficulties were encountered throughout the manufacturing process , a successful investment casting procedure was eventually developed. Wax formulation and pattern assembly, shell mold processing, and counter gravity casting techniques were developed. Ten IN-718 lattice block castings (each measuring 15-cm wide by 30-cm long by 1.2-cm thick) have been successfully produced by Hitchiner Gas Turbine Division, Milford, New Hampshire, using their patented counter gravity casting techniques. Details of the processing and resulting microstructures are discussed in this paper. Post casting processing and evaluation of system specific mechanical properties of these specimens are in progress.

  18. Pitting corrosion resistant austenite stainless steel

    DOEpatents

    van Rooyen, D.; Bandy, R.

    A pitting corrosion resistant austenite stainless steel comprises 17 to 28 wt. % chromium, 15 to 26 wt. % nickel, 5 to 8 wt. % molybdenum, and 0.3 to 0.5 wt. % nitrogen, the balance being iron, unavoidable impurities, minor additions made in the normal course of melting and casting alloys of this type, and may optionally include up to 10 wt. % of manganese, up to 5 wt. % of silicon, and up to 0.08 wt. % of carbon.

  19. Project CAST.

    ERIC Educational Resources Information Center

    Charles County Board of Education, La Plata, MD. Office of Special Education.

    The document outlines procedures for implementing Project CAST (Community and School Together), a community-based career education program for secondary special education students in Charles County, Maryland. Initial sections discuss the role of a learning coordinator, (including relevant travel reimbursement and mileage forms) and an overview of…

  20. Duplex Direct Data Distribution System

    NASA Technical Reports Server (NTRS)

    Greenfield, Israel (Technical Monitor)

    2001-01-01

    The NASA Glenn Research Center (GRC) is developing and demonstrating communications and network technologies that are helping to enable the near-Earth space Internet. GRC envisions several service categories. The first of these categories is direct data distribution or D3 (pronounced "D-cubed"). Commercially provided D3 will make it possible to download a data set from a spacecraft, like the International Space Station. as easily as one can extract a file from a remote server today, using a file transfer protocol. In a second category, NASA spacecraft will make use of commercial satellite communication (SATCOM) systems. Some of those services will come from purchasing time on unused transponders that cover landmasses. While it is likely there will be gaps in service coverage, Internet services should be available using these systems. This report addresses alternative methods of implementing a full duplex enhancement of the GRC developed experimental Ka-Band Direct Data Distribution (D3) space-to-ground communication link. The resulting duplex version is called the Duplex Direct Data Distribution (D4) system. The D4 system is intended to provide high-data-rate commercial direct or internet-based communications service between the NASA spacecraft in low earth orbit (LEO) and the respective principal investigators associated with these spacecraft. Candidate commercial services were assessed regarding their near-term potential to meet NASA requirements. Candidates included Ka-band and V-band geostationary orbit and non-geostationary orbit satellite relay services and direct downlink ("LEO teleport") services. End-to-end systems concepts were examined and characterized in terms of alternative link layer architectures. Alternatives included a Direct Link, a Relay Link, a Hybrid Link, and a Dual Mode Link. The direct link assessment examined sample ground terminal placements and antenna angle issues. The SATCOM-based alternatives examined existing or proposed commercial

  1. Casting methods

    DOEpatents

    Marsden, Kenneth C.; Meyer, Mitchell K.; Grover, Blair K.; Fielding, Randall S.; Wolfensberger, Billy W.

    2012-12-18

    A casting device includes a covered crucible having a top opening and a bottom orifice, a lid covering the top opening, a stopper rod sealing the bottom orifice, and a reusable mold having at least one chamber, a top end of the chamber being open to and positioned below the bottom orifice and a vacuum tap into the chamber being below the top end of the chamber. A casting method includes charging a crucible with a solid material and covering the crucible, heating the crucible, melting the material, evacuating a chamber of a mold to less than 1 atm absolute through a vacuum tap into the chamber, draining the melted material into the evacuated chamber, solidifying the material in the chamber, and removing the solidified material from the chamber without damaging the chamber.

  2. CASTING APPARATUS

    DOEpatents

    Gray, C.F.; Thompson, R.H.

    1958-09-23

    An apparatus is described for casting small quantities of uranlum. It consists of a crucible having a hole in the bottom with a mold positioned below. A vertical rcd passes through the hole in the crucible and has at its upper end a piercing head adapted to break the oxide skin encasing a molten uranium body. An air tight cylinder surrounds the crucible and mold, and is arranged to be evacuated.

  3. Casting materials

    DOEpatents

    Chaudhry, Anil R.; Dzugan, Robert; Harrington, Richard M.; Neece, Faurice D.; Singh, Nipendra P.

    2011-06-14

    A foam material comprises a liquid polymer and a liquid isocyanate which is mixed to make a solution that is poured, injected or otherwise deposited into a corresponding mold. A reaction from the mixture of the liquid polymer and liquid isocyanate inside the mold forms a thermally collapsible foam structure having a shape that corresponds to the inside surface configuration of the mold and a skin that is continuous and unbroken. Once the reaction is complete, the foam pattern is removed from the mold and may be used as a pattern in any number of conventional casting processes.

  4. Stainless steel cookware as a significant source of nickel, chromium, and iron.

    PubMed

    Kuligowski, J; Halperin, K M

    1992-08-01

    Stainless steels are widely used materials in food preparation and in home and commercial cookware. Stainless is readily attacked by organic acids, particularly at cooking temperatures; hence iron, chromium, and nickel should be released from the material into the food. Nickel is implicated in numerous health problems, notably allergic contact dermatitis. Conversely, chromium and iron are essential nutrients for which stainless could be a useful source. Home cookware was examined by atomic absorption spectroscopy: seven different stainless utensils as well as cast iron, mild steel, aluminum and enamelled steel. The materials were exposed to mildly acidic conditions at boiling temperature. Nickel was a major corrosion product from stainless steel utensils; chromium and iron were also detected. It is recommended that nickel-sensitive patients switch to a material other than stainless, and that the stainless steel cookware industry seriously consider switching to a non-nickel formulation.

  5. Molecular duplexes with encoded sequences and stabilities.

    PubMed

    Gong, Bing

    2012-12-18

    Through specific molecular shapes and repeating polymeric sequences, biomacromolecules encode information about both structure and function. Inspired by DNA molecules, we have conceived a strategy to encode linear molecular strands with sequences that specify intermolecular association, and we and our collaborators have supported this idea through our experimental work. This Account summarizes the design and development of a class of molecular duplexes with programmable hydrogen-bonding sequences and adjustable stabilities. The specific system involves oligoamide strands synthesized from readily available monomeric modules based on standard amide (peptide) chemistry. By covalently linking three types of basic building blocks in different orders, we create oligoamide strands with various arrangements of amide O and H atoms that provide arrays of hydrogen bonding sequences. Because one of the two edges of these molecules presents the sequences of hydrogen-bond donors and acceptors, these oligoamide strands associate via their hydrogen-bonding edges into double-stranded pairs or duplexes. Systematic studies have demonstrated the strict sequence specificity and tunable stability of this system. These structurally simple duplexes exhibit many features associated with DNA sequences such as programmable sequence specificity, shape and hydrogen-bonding complementarity, and cooperativity of multipoint interactions. Capable of specifying intermolecular associations, these duplexes have formed supramolecular structures such as β-sheets and non-covalent block copolymers and have templated chemical reactions. The incorporation of dynamic covalent interactions into these H-bonded duplexes has created association units that undergo sequence-specific association and covalent ligation in both nonpolar solvents and polar media including water. These new association units may facilitate the development of new dynamic covalent structures, and new properties are emerging from these

  6. Duplex sampling apparatus and method

    DOEpatents

    Brown, Paul E.; Lloyd, Robert

    1992-01-01

    An improved apparatus is provided for sampling a gaseous mixture and for measuring mixture components. The apparatus includes two sampling containers connected in series serving as a duplex sampling apparatus. The apparatus is adapted to independently determine the amounts of condensable and noncondensable gases in admixture from a single sample. More specifically, a first container includes a first port capable of selectively connecting to and disconnecting from a sample source and a second port capable of selectively connecting to and disconnecting from a second container. A second container also includes a first port capable of selectively connecting to and disconnecting from the second port of the first container and a second port capable of either selectively connecting to and disconnecting from a differential pressure source. By cooling a mixture sample in the first container, the condensable vapors form a liquid, leaving noncondensable gases either as free gases or dissolved in the liquid. The condensed liquid is heated to drive out dissolved noncondensable gases, and all the noncondensable gases are transferred to the second container. Then the first and second containers are separated from one another in order to separately determine the amount of noncondensable gases and the amount of condensable gases in the sample.

  7. Metallic Reinforcement of Direct Squeeze Die Casting Aluminum Alloys for Improved Strength and Fracture Resistance

    SciTech Connect

    D. Schwam: J.F. Wallace: Y. Zhu: J.W. Ki

    2004-10-01

    The utilization of aluminum die casting as enclosures where internal equipment is rotating inside of the casting and could fracture requires a strong housing to restrain the fractured parts. A typical example would be a supercharger. In case of a failure, unless adequately contained, fractured parts could injure people operating the equipment. A number of potential reinforcement materials were investigated. The initial work was conducted in sand molds to create experimental conditions that promote prolonged contact of the reinforcing material with molten aluminum. Bonding of Aluminum bronze, Cast iron, and Ni-resist inserts with various electroplated coatings and surface treatments were analyzed. Also toughening of A354 aluminum cast alloy by steel and stainless steel wire mesh with various conditions was analyzed. A practical approach to reinforcement of die cast aluminum components is to use a reinforcing steel preform. Such performs can be fabricated from steel wire mesh or perforated metal sheet by stamping or deep drawing. A hemispherical, dome shaped casting was selected in this investigation. A deep drawing die was used to fabricate the reinforcing performs. The tendency of aluminum cast enclosures to fracture could be significantly reduced by installing a wire mesh of austenitic stainless steel or a punched austenitic stainless steel sheet within the casting. The use of reinforcements made of austenitic stainless steel wire mesh or punched austenitic stainless steel sheet provided marked improvement in reducing the fragmentation of the casting. The best strengthening was obtained with austenitic stainless steel wire and with a punched stainless steel sheet without annealing this material. Somewhat lower results were obtained with the annealed punched stainless steel sheet. When the annealed 1020 steel wire mesh was used, the results were only slightly improved because of the lower mechanical properties of this unalloyed steel. The lowest results were

  8. FACILITY 810, REAR OF DUPLEX SHOWING COURTYARD BETWEEN WINGS, OBLIQUE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    FACILITY 810, REAR OF DUPLEX SHOWING COURTYARD BETWEEN WINGS, OBLIQUE VIEW FACING EAST. - Schofield Barracks Military Reservation, Duplex Housing Type with Corner Entries, Between Hamilton & Tidball Streets near Williston Avenue, Wahiawa, Honolulu County, HI

  9. Extensional duplex in the Purcell Mountains of southeastern British Columbia

    SciTech Connect

    Root, K.G. )

    1990-05-01

    An extensional duplex consisting of fault-bounded blocks (horses) located between how-angle normal faults is exposed in Proterozoic strata in the Purcell Mountains of British Columbia, Canada. This is one of the first documented extensional duplexes, and it is geometrically and kinematically analogous to duplexes developed in contractional and strike-slip fault systems. The duplex formed within an extensional fault with a ramp and flat geometry when horses were sliced from the ramp and transported within the fault system.

  10. Thin Wall Iron Castings

    SciTech Connect

    J.F. Cuttino; D.M. Stefanescu; T.S. Piwonka

    2001-10-31

    Results of an investigation made to develop methods of making iron castings having wall thicknesses as small as 2.5 mm in green sand molds are presented. It was found that thin wall ductile and compacted graphite iron castings can be made and have properties consistent with heavier castings. Green sand molding variables that affect casting dimensions were also identified.

  11. Full-duplex optical communication system

    NASA Technical Reports Server (NTRS)

    Shay, Thomas M. (Inventor); Hazzard, David A. (Inventor); Horan, Stephen (Inventor); Payne, Jason A. (Inventor)

    2004-01-01

    A method of full-duplex electromagnetic communication wherein a pair of data modulation formats are selected for the forward and return data links respectively such that the forward data electro-magnetic beam serves as a carrier for the return data. A method of encoding optical information is used wherein right-hand and left-hand circular polarizations are assigned to optical information to represent binary states. An application for an earth to low earth orbit optical communications system is presented which implements the full-duplex communication and circular polarization keying modulation format.

  12. Subcritical Measurements Multiple HEU Metal Castings

    SciTech Connect

    Mihalczo, John T; Archer, Daniel E; Wright, Michael C

    2008-01-01

    Experiments with the standard annular highly enriched uranium (HEU) metal castings at Y-12 were performed in which up to 5 castings ({approx}90kg) were assembled in a tightly packed array with minimal spacing between castings. The fission chain multiplication process was initiated by a time tagged {sup 253}Cf spontaneously fissioning neutron source or time and directionally tagged neutrons from a small portable DT neutron generator and the prompt neutron time behavior measured with plastic scintillation detectors sensitive the fast neutron (>1 MeV) and gamma ray without distinction. These experiments were performed to provide data to benchmark methods for the calculation of the prompt neutron time behavior. Previous measurements with a single casting have been reported. This paper presents the experimental results for multiple castings. The prompt time decay was obtained by time coincidence correlation measurements between the detectors and the time tagged neutron source emission (equivalent to randomly pulsed neutron measurements) and between pairs of plastic scintillation detectors (equivalent to a 2-detector Rossi-alpha measurement). These standard HEU storage castings at the Y-12 plant had 5.000-in-OD, 3.500-in-ID, masses between 17,636 and 17,996 g, impurity content of 992 ppm, density of 18.75 g/cm{sup 3} and average enrichment of 93.16 wt % {sup 235}U. The castings were in tight fitting 025-in.-thick, 8.0-in-high stainless steel (SS-304) cylindrical cans for contamination control which were 8.0 in high. One can had an inside diameter of 3.0 in so that the Cf source could be located on the axes of this casting. Four 1 x 1 x 6 in plastic scintillators with the long dimension perpendicular to axes of the castings and adjacent to the outer surface of the casting cans were used. The detectors were enclosed in 1/4.-in.-thick lead shields on four 1 x 6 surfaces and on the 1 x 1 surface. The small surface of the lead shield was adjacent to the steel table. The

  13. Development of high-strength, high-corrosion resistant austenitic stainless steel for sour gas service

    SciTech Connect

    Nakayama, T.; Fujiwara, K.; Torii, Y.; Inoue, T.

    1988-01-01

    An austenitic stainless steel for sour gas service has been developed. The new steel has been shown to offer high strength, i.e., 0.2% PS exceeding 42kgf/mm/sup 2/ (414MPa) under solution-annealed conditions, along with excellent resistance to sulphide stress corrosion cracking, pitting corrosion, and crevice corrosion, in comparison with conventional martensitic stainless steel such as CA-6NM, duplex stainless steel such as ASTM A790 UNS S31803, and austenitic stainless steels such as Type 316. Its higher resistance to corrosion cracking, etc., then Type 316 was thought to be attributable to the higher contents of Cr, Mo, and N, which help to form more stable passive film in a shorter time.

  14. Comparison of Stress Corrosion Cracking Susceptibility of Laser Machined and Milled 304 L Stainless Steel

    NASA Astrophysics Data System (ADS)

    Gupta, R. K.; Kumar, Aniruddha; Nagpure, D. C.; Rai, S. K.; Singh, M. K.; Khooha, Ajay; Singh, A. K.; Singh, Amrendra; Tiwari, M. K.; Ganesh, P.; Kaul, R.; Singh, B.

    2016-07-01

    Machining of austenitic stainless steel components is known to introduce significant enhancement in their susceptibility to stress corrosion cracking. The paper compares stress corrosion cracking susceptibility of laser machined 304 L stainless steel specimens with conventionally milled counterpart in chloride environment. With respect to conventionally milled specimens, laser machined specimens displayed more than 12 times longer crack initiation time in accelerated stress corrosion cracking test in boiling magnesium chloride as per ASTM G36. Reduced stress corrosion cracking susceptibility of laser machined surface is attributed to its predominantly ferritic duplex microstructure in which anodic ferrite phase was under compressive stress with respect to cathodic austenite.

  15. Corrosion of Stainless-Steel Tubing in a Spacecraft Launch Environment

    NASA Technical Reports Server (NTRS)

    Barile, Ronald G.; MacDowell, Louis G.; Curran, Joe; Calle, Luz Maria; Hodge, Timothy

    2001-01-01

    This is a report of exposure of various metal tubing to oceanfront launch environments. The objective is to examine various types of corrosion-resistant tubing for Space Shuttle launch sites. The metals were stainless steels (austenitic, low-carbon, Mo-alloy, superaustenitic, duplex, and superferritic), Ni-Cr-Mo alloy, Ni-Mo-Cr-Fe-W alloy, and austenitic Ni-base superalloy.

  16. Ultra-short silicon MMI duplexer

    NASA Astrophysics Data System (ADS)

    Yi, Huaxiang; Huang, Yawen; Wang, Xingjun; Zhou, Zhiping

    2012-11-01

    The fiber-to-the-home (FTTH) systems are growing fast these days, where two different wavelengths are used for upstream and downstream traffic, typically 1310nm and 1490nm. The duplexers are the key elements to separate these wavelengths into different path in central offices (CO) and optical network unit (ONU) in passive optical network (PON). Multimode interference (MMI) has some benefits to be a duplexer including large fabrication tolerance, low-temperature dependence, and low-polarization dependence, but its size is too large to integrate in conventional case. Based on the silicon photonics platform, ultra-short silicon MMI duplexer was demonstrated to separate the 1310nm and 1490nm lights. By studying the theory of self-image phenomena in MMI, the first order images are adopted in order to keep the device short. A cascaded MMI structure was investigated to implement the wavelength splitting, where both the light of 1310nm and 1490nm was input from the same port, and the 1490nm light was coupling cross the first MMI and output at the cross-port in the device while the 1310nm light was coupling through the first and second MMI and output at the bar-port in the device. The experiment was carried on with the SOI wafer of 340nm top silicon. The cascaded MMI was investigated to fold the length of the duplexer as short as 117μm with the extinct ratio over 10dB.

  17. Plastic casting resin poisoning

    MedlinePlus

    Epoxy poisoning; Resin poisoning ... Epoxy and resin can be poisonous if they are swallowed or their fumes are breathed in. ... Plastic casting resins are found in various plastic casting resin products.

  18. Cool Cast Facts

    MedlinePlus

    ... outer layer is usually made of plaster or fiberglass. Fiberglass casts are made of fiberglass, which is a plastic that can be shaped. Fiberglass casts come in many different colors — if you' ...

  19. Electromagnetic Casting of Copper Alloys

    NASA Astrophysics Data System (ADS)

    Tyler, D. E.; Lewis, B. G.; Renschen, P. D.

    1985-09-01

    Electromagnetic (EMC) casting technology has been successfully developed for copper base alloys. This casting technique eliminates the mold related defects normally encountered in direct chill (DC) mold casting, and provides castings with greatly improved hot workability.

  20. LLNL casting technology

    SciTech Connect

    Shapiro, A.B.; Comfort, W.J. III

    1994-01-01

    Competition to produce cast parts of higher quality, lower rejection rate, and lower cost is a fundamental factor in the global economy. To gain an edge on foreign competitors, the US casting industry must cut manufacturing costs and reduce the time from design to market. Casting research and development (R&D) are the key to increasing US compentiveness in the casting arena. Lawrence Livermore National Laboratory (LLNL) is the home of a wide range of R&D projects that push the boundaries of state-of-the art casting. LLNL casting expertise and technology include: casting modeling research and development, including numerical simulation of fluid flow, heat transfer, reaction/solidification kinetics, and part distortion with residual stresses; special facilities to cast toxic material; extensive experience casting metals and nonmetals; advanced measurement and instrumentation systems. Department of Energy (DOE) funding provides the leverage for LLNL to collaborate with industrial partners to share this advanced casting expertise and technology. At the same time, collaboration with industrial partners provides LLNL technologists with broader insights into casting industry issues, casting process data, and the collective, experience of industry experts. Casting R&D is also an excellent example of dual-use technology; it is the cornerstone for increasing US industrial competitiveness and minimizing waste nuclear material in weapon component production. Annual funding for casting projects at LLNL is $10M, which represents 1% of the total LLNL budget. Metal casting accounts for about 80% of the funding. Funding is nearly equally divided between development directed toward US industrial competitiveness and weapon component casting.

  1. LLNL casting technology

    NASA Astrophysics Data System (ADS)

    Shapiro, A. B.; Comfort, W. J., III

    1994-01-01

    Competition to produce cast parts of higher quality, lower rejection rate, and lower cost is a fundamental factor in the global economy. To gain an edge on foreign competitors, the US casting industry must cut manufacturing costs and reduce the time from design to market. Casting research and development (R&D) are the key to increasing US competiveness in the casting arena. Lawrence Livermore National Laboratory (LLNL) is the home of a wide range of R&D projects that push the boundaries of state-of-the art casting. LLNL casting expertise and technology include: casting modeling research and development, including numerical simulation of fluid flow, heat transfer, reaction/solidification kinetics, and part distortion with residual stresses; special facilities to cast toxic material; extensive experience casting metals and nonmetals; advanced measurement and instrumentation systems. Department of Energy (DOE) funding provides the leverage for LLNL to collaborate with industrial partners to share this advanced casting expertise and technology. At the same time, collaboration with industrial partners provides LLNL technologists with broader insights into casting industry issues, casting process data, and the collective experience of industry experts. Casting R&D is also an excellent example of dual-use technology; it is the cornerstone for increasing US industrial competitiveness and minimizing waste nuclear material in weapon component production. Annual funding for casting projects at LLNL is $10M, which represents 1% of the total LLNL budget. Metal casting accounts for about 80% of the funding. Funding is nearly equally divided between development directed toward US industrial competitiveness and weapon component casting.

  2. Predicting Pattern Tooling and Casting Dimensions for Investment Casting, Phase III

    SciTech Connect

    Sabau, Adrian S

    2008-04-01

    Efforts during Phase III focused mainly on the shell-alloy systems. A high melting point alloy, 17-4PH stainless steel, was considered. The experimental part of the program was conducted at ORNL and commercial foundries, where wax patterns were injected, molds were invested, and alloys were poured. Shell molds made of fused-silica and alumino-silicates were considered. A literature review was conducted on thermophysical and thermomechanical properties alumino-silicates. Material property data, which were not available from material suppliers, was obtained. For all the properties of 17-4PH stainless steel, the experimental data available in the literature did not cover the entire temperature range necessary for process simulation. Thus, some material properties were evaluated using ProCAST, based on CompuTherm database. A comparison between the predicted material property data and measured property data was made. It was found that most material properties were accurately predicted only over several temperature ranges. No experimental data for plastic modulus were found. Thus, several assumptions were made and ProCAST recommendations were followed in order to obtain a complete set of mechanical property data at high temperatures. Thermal expansion measurements for the 17-4PH alloy were conducted during heating and cooling. As a function of temperature, the thermal expansion for both the alloy and shell mold materials showed different evolution on heating and cooling. Numerical simulations were performed using ProCAST for the investment casting of 17-4PH stainless steel parts in fused silica molds using the thermal expansion obtained on heating and another one with thermal expansion obtained on cooling. Since the fused silica shells had the lowest thermal expansion properties in the industry, the dewaxing phase, including the coupling between wax-shell systems, was neglected. The shell mold was considered to be a pure elastic material. The alloy dimensions were

  3. Energy Saving Melting andRevert Reduction Technology (E0SMARRT): Predicting Pattern Tooling and Casting Dimension for Investment Casting

    SciTech Connect

    Nick Cannell; Dr. Mark Samonds; Adi Sholapurwalla; Sam Scott

    2008-11-21

    The investment casting process is an expendable mold process where wax patterns of the part and rigging are molded, assembled, shelled and melted to produce a ceramic mold matching the shape of the component to be cast. Investment casting is an important manufacturing method for critical parts because of the ability to maintain dimensional shape and tolerances. However, these tolerances can be easily exceeded if the molding components do not maintain their individual shapes well. In the investment casting process there are several opportunities for the final casting shape to not maintain the intended size and shape, such as shrinkage of the wax in the injection tool, the modification of the shape during shell heating, and with the thermal shrink and distortion in the casting process. Studies have been completed to look at the casting and shell distortions through the process in earlier phases of this project. Dr. Adrian Sabau at Oak Ridge National Labs performed characterizations and validations of 17-4 PH stainless steel in primarily fused silica shell systems with good agreement between analysis results and experimental data. Further tasks provided material property measurements of wax and methodology for employing a viscoelastic definition of wax materials into software. The final set of tasks involved the implementation of the findings into the commercial casting analysis software ProCAST, owned and maintained by ESI Group. This included: o the transfer of the wax material property data from its raw form into separate temperature-dependent thermophysical and mechanical property datasets o adding this wax material property data into an easily viewable and modifiable user interface within the pre-processing application of the ProCAST suite, namely PreCAST o and validating the data and viscoelastic wax model with respect to experimental results

  4. Parallel thermodynamic analysis of duplexes on oligodeoxyribonucleotide microchips.

    SciTech Connect

    Fotin, A. V.; Drobyshev, A. L.; Proudnikov, D. Y.; Perov, A. N.; Mirzabekov, A. D.; Center for Mechanistic Biology and Biotechnology; Engelhardt Inst. of Molecular Biology

    1998-03-15

    A microchip method has been developed for massive and parallel thermodynamic analyses of DNA duplexes. Fluorescently labeled oligonucleotides were hybridized with oligonucleotides immobilized in the 100 x 100 x 20 mum gel pads of the microchips. The equilibrium melting curves for all microchip duplexes were measured in real time in parallel for all microchip duplexes. Thermodynamic data for perfect and mismatched duplexes that were obtained using the microchip method directly correlated with data obtained in solution. Fluorescent labels or longer linkers between the gel and the oligonucleotides appeared to have no significant effect on duplex stability. Extending the immobilized oligonucleotides with a four-base mixture from the 3'-end or one or two universal bases (5-nitroindole) from the 3'- and/or 5'- end increased the stabilities of their duplexes. These extensions were applied to increase the stabilities of the duplexes formed with short oligonucleotides in microchips, to significantly lessen the differences in melting curves of the AT- and GC-rich duplexes, and to improve discrimination of perfect duplexes from those containing poorly recognized terminal mismatches. This study explored a way to increase the efficiency of sequencing by hybridization on oligonucleotide microchips.

  5. Effect of shielding gas composition on the properties of hyperbaric GMA welds in duplex steels

    SciTech Connect

    Ware, N.; Dos Santos, J.F.; Richardson, I.

    1994-12-31

    By using Ar/He based shielding gas mixtures with a variety of oxygen and nitrogen additions the absorption of active gas components into duplex stainless steels welded under hyperbaric conditions was examined. The pressure levels used corresponded to seawater depths of 100m, 200m and 300m. The GMAW process in the short circuit transfer mode was used for all tests. Both bead-on-plate and ``V`` butt joints were carried out. The effect of variations in the weld metal active gas components on the weld metal chemical composition and phase balance was investigated. In a second set of tests the effect of varying heat inputs on the phase balance and microstructure was assessed.

  6. Development of high-strength, high-corrosion-resistant austenitic stainless steel for sour-gas service

    SciTech Connect

    Nakayama, T. ); Fujiwara, K.; Torii, Y. ); Inoue, T. )

    1989-09-01

    This paper reports the development of an austenitic stainless steel for sour-gas service. The new steel has been shown to offer high strength, i.e., 0.2% PS exceeding 42 kgf/mm{sup 2} (414 MPa) under solution-annealed conditions, along with excellent resistance to sulfide stress corrosion cracking, pitting corrosion, and crevice corrosion, in comparison with conventional martensitic stainless steels such as CA-6NM, duplex stainless steels such as ASTM A790 (UNS S31803), and austenitic stainless steels such as type 316 (UNS S31600). Its higher resistance to corrosion cracking, etc., than type 316 was thought to be attributable to the higher contents of Cr, Mo, and N, which help to form more stable passive film in a shorter time.

  7. Creep Behavior of a New Cast Austenitic Alloy

    SciTech Connect

    Shingledecker, John P; Maziasz, Philip J; Evans, Neal D; Pollard, Michael J

    2007-01-01

    A new cast austenitic alloy, CF8C-Plus, has been developed by Oak Ridge National Laboratory (ORNL) and Caterpillar for a wide range of high temperature applications including diesel exhaust components and turbine casings. The creep strength of the CF8C-Plus steel is much greater than that of the standard cast CF8C stainless steel and is comparable to the highest strength wrought commercial austenitic stainless steels and alloys, such as NF709. The creep properties of CF8C-Plus are discussed in terms of the alloy design methodology and the evaluation of some long-term creep tested specimens (over 20,000 hours). Microcharacterization shows that the excellent creep strength is due mainly to the precipitation of very fine nano-scale and stable MC carbides, without the formation of deleterious intermetallic phases.

  8. Expandable pattern casting research

    NASA Astrophysics Data System (ADS)

    1993-09-01

    The Expandable Pattern Casting (EPC) Process is a developing foundry technology that allows designers the opportunity to consolidate parts, reduce machining, and minimize assembly operations. An air gauging system was developed for measuring foam patterns; exact shrinkage depended on type and density of the foam. Compaction studies showed that maximum sand densities in cavities and under overhangs are achieved with vibrational amplitudes 0.001-0.004 in., and that sand moved most freely within a few inches of the top free surface. Key to complete mold filling while minimizing casting defects lies in removing the foam decomposition products. The most precise iron castings were made by EPC in four commercial EPC foundries, with attention paid to molding and compaction. EP cast 60-45-12 ductile iron had yield strengths, ultimate strengths, and elastic modulus similar to conventionally cast ductile iron cast from the same ladle.

  9. Full Duplex, Spread Spectrum Radio System

    NASA Technical Reports Server (NTRS)

    Harvey, Bruce A.

    2000-01-01

    The goal of this project was to support the development of a full duplex, spread spectrum voice communications system. The assembly and testing of a prototype system consisting of a Harris PRISM spread spectrum radio, a TMS320C54x signal processing development board and a Zilog Z80180 microprocessor was underway at the start of this project. The efforts under this project were the development of multiple access schemes, analysis of full duplex voice feedback delays, and the development and analysis of forward error correction (FEC) algorithms. The multiple access analysis involved the selection between code division multiple access (CDMA), frequency division multiple access (FDMA) and time division multiple access (TDMA). Full duplex voice feedback analysis involved the analysis of packet size and delays associated with full loop voice feedback for confirmation of radio system performance. FEC analysis included studies of the performance under the expected burst error scenario with the relatively short packet lengths, and analysis of implementation in the TMS320C54x digital signal processor. When the capabilities and the limitations of the components used were considered, the multiple access scheme chosen was a combination TDMA/FDMA scheme that will provide up to eight users on each of three separate frequencies. Packets to and from each user will consist of 16 samples at a rate of 8,000 samples per second for a total of 2 ms of voice information. The resulting voice feedback delay will therefore be 4 - 6 ms. The most practical FEC algorithm for implementation was a convolutional code with a Viterbi decoder. Interleaving of the bits of each packet will be required to offset the effects of burst errors.

  10. SLIP CASTING METHOD

    DOEpatents

    Allison, A.G.

    1959-09-01

    S>A process is described for preparing a magnesium oxide slip casting slurry which when used in conjunction with standard casting techniques results in a very strong "green" slip casting and a fired piece of very close dimensional tolerance. The process involves aging an aqueous magnestum oxide slurry, having a basic pH value, until it attains a specified critical viscosity at which time a deflocculating agent is added without upsetting the basic pH value.

  11. Articles comprising ferritic stainless steels

    DOEpatents

    Rakowski, James M.

    2016-06-28

    An article of manufacture comprises a ferritic stainless steel that includes a near-surface region depleted of silicon relative to a remainder of the ferritic stainless steel. The article has a reduced tendency to form an electrically resistive silica layer including silicon derived from the steel when the article is subjected to high temperature oxidizing conditions. The ferritic stainless steel is selected from the group comprising AISI Type 430 stainless steel, AISI Type 439 stainless steel, AISI Type 441 stainless steel, AISI Type 444 stainless steel, and E-BRITE.RTM. alloy, also known as UNS 44627 stainless steel. In certain embodiments, the article of manufacture is a fuel cell interconnect for a solid oxide fuel cell.

  12. Methods And Devices For Characterizing Duplex Nucleic Acid Molecules

    DOEpatents

    Akeson, Mark; Vercoutere, Wenonah; Haussler, David; Winters-Hilt, Stephen

    2005-08-30

    Methods and devices are provided for characterizing a duplex nucleic acid, e.g., a duplex DNA molecule. In the subject methods, a fluid conducting medium that includes a duplex nucleic acid molecule is contacted with a nanopore under the influence of an applied electric field and the resulting changes in current through the nanopore caused by the duplex nucleic acid molecule are monitored. The observed changes in current through the nanopore are then employed as a set of data values to characterize the duplex nucleic acid, where the set of data values may be employed in raw form or manipulated, e.g., into a current blockade profile. Also provided are nanopore devices for practicing the subject methods, where the subject nanopore devices are characterized by the presence of an algorithm which directs a processing means to employ monitored changes in current through a nanopore to characterize a duplex nucleic acid molecule responsible for the current changes. The subject methods and devices find use in a variety of applications, including, among other applications, the identification of an analyte duplex DNA molecule in a sample, the specific base sequence at a single nulceotide polymorphism (SNP), and the sequencing of duplex DNA molecules.

  13. 52. Photocopy of copy of original Officers' Duplex Quarters drawing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    52. Photocopy of copy of original Officers' Duplex Quarters drawing by Copeland, 7 April 1932 (Original in possession of Veterans Administration, Wichita, Kansas, copy at Ablah Library, Wichita State University). Heating - Veterans Administration Center, Officers Duplex Quarters, 5302 East Kellogg (Legal Address); 5500 East Kellogg (Common Address), Wichita, Sedgwick County, KS

  14. 51. Photocopy of copy of original Officers' Duplex Quarters drawing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    51. Photocopy of copy of original Officers' Duplex Quarters drawing by B.S. Elliott, 7 April 1932 (original in possession of Veterans Administration, Wichita, Kansas, copy at Ablah Library, Wichita State University). Plumbing - Veterans Administration Center, Officers Duplex Quarters, 5302 East Kellogg (Legal Address); 5500 East Kellogg (Common Address), Wichita, Sedgwick County, KS

  15. Scintigraphic features of duplex kidneys on DMSA renal cortical scans.

    PubMed

    Kwatra, Neha; Shalaby-Rana, Eglal; Majd, Massoud

    2013-09-01

    The spectrum of manifestations of duplex kidneys on (99m)Tc-dimercaptosuccinic acid (DMSA) renal cortical scans and correlating findings on other imaging modalities are presented. Relevant embryology of the duplex systems and technical aspects of DMSA scintigraphy are reviewed.

  16. 48. Photocopy of copy of original Officers' Duplex Quarters drawing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    48. Photocopy of copy of original Officers' Duplex Quarters drawing by Turner, 7 April 1932 (original in possession of Veterans Administration, Wichita, Kansas, copy at Ablah Library, Wichita State University). Attic and roof, basement, first floor, and second floor plans - Veterans Administration Center, Officers Duplex Quarters, 5302 East Kellogg (Legal Address); 5500 East Kellogg (Common Address), Wichita, Sedgwick County, KS

  17. 50. Photocopy of copy of original Officers' Duplex Quarters drawing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    50. Photocopy of copy of original Officers' Duplex Quarters drawing by Turner, 7 April 1932 (original in possession of Veterans Administration, Wichita, Kansas, copy at Ablah Library, Wichita State University. Detail of front entrance and of gable dormer - Veterans Administration Center, Officers Duplex Quarters, 5302 East Kellogg (Legal Address); 5500 East Kellogg (Common Address), Wichita, Sedgwick County, KS

  18. 49. Photocopy of copy of original Officers' Duplex Quarters drawing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    49. Photocopy of copy of original Officers' Duplex Quarters drawing by Turner, 7 April 1932 (original in possession of Veterans Administration, Wichita, Kansas, copy at Ablah Library, Wichita State University). Front, rear, and side elevations, and cross-section - Veterans Administration Center, Officers Duplex Quarters, 5302 East Kellogg (Legal Address); 5500 East Kellogg (Common Address), Wichita, Sedgwick County, KS

  19. Acoustical and perceptual influence of duplex stringing in grand pianos.

    PubMed

    Öberg, Fredrik; Askenfelt, Anders

    2012-01-01

    This study investigates the acoustical and perceptual influence of the string parts outside the speaking length in grand pianos (front and rear duplex strings). Acoustical measurements on a grand piano in concert condition were conducted, measuring the fundamental frequencies of all main and duplex strings in the four octaves D4-C8. Considerable deviations from the nominal harmonic relations between the rear duplex and main string frequencies, as described by the manufacturer in a patent, were observed. Generally the rear duplex strings were tuned higher than the nominal harmonic relations with average and median deviations approaching +50 cent. Single keys reached +190 and -100 cent. The spread in deviation from harmonic relations within trichords was also substantial with average and median values around 25 cent, occasionally reaching 60 cent. Contributions from both front and rear duplex strings were observed in the bridge motion and sound. The audibility of the duplex strings was studied in an ABX listening test. Complete dampening of the front duplex was clearly perceptible both for an experiment group consisting of musicians and a control group with naive subjects. The contribution from the rear duplex could also be perceived, but less pronounced. PMID:22280708

  20. Chromium-Makes stainless steel stainless

    USGS Publications Warehouse

    Kropschot, S.J.; Doebrich, Jeff

    2010-01-01

    Chromium, a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point, is a silvery white, hard, and bright metal plating on steel and other material. Commonly known as chrome, it is one of the most important and indispensable industrial metals because of its hardness and resistance to corrosion. But it is used for more than the production of stainless steel and nonferrous alloys; it is also used to create pigments and chemicals used to process leather.

  1. Duplex structures connecting fault segments in Entrada Sandstone

    NASA Astrophysics Data System (ADS)

    Cruikshank, Kenneth M.; Zhao, Guozhu; Johnson, Arvid M.

    All stages in the development of a duplex structure—from isolated, stepped fault segments, to segments joined by a single ramp, to segments joined by tens of ramps—are preserved along strike-slip and normal faults in Entrada Sandstone in Arches National Park, Utah. Bedding is either absent or at a high angle to the duplex-like structures in Entrada Sandstone, thus it had no significant role in constraining their geometry. We can reproduce the essential features of a duplex structure along a normal fault with mechanical and kinematic models previously used to simulate duplex structures along thrust faults. However the models do not account for the amount of observed thickening at the step where the structure forms. This suggests that the geometry of duplex-like structures along these strike-slip faults may be a result of interaction between the fault segments.

  2. Textures of strip cast Fe16%Cr

    SciTech Connect

    Raabe, D.; Reher, F.; Luecke, K. ); Hoelscher, M. )

    1993-07-01

    Ferritic stainless steels with a Cr content of 16% are mainly manufactured by continuous casting, hot rolling, cold rolling and final recrystallization. The recent development of the strip casting method, which provides sheets with an equivalent geometry, i.e. thickness and width as the hot rolled band, yields significant improvements in comparison to the conventional processing. The weak initial strip texture and the homogeneous microstructure through the sample thickness have shown evidence of avoiding the well known ridging phenomenon of the finally rolled and annealed product. The occurrence of ridging in conventionally processed FeCr steel has been attributed to the collective shear of grains with (hkl)<110>, i.e. [alpha]-fibre orientations, which become oriented and topologically arranged during hot rolling. In the present paper the textures of a stainless ferritic steel with 16% Cr and 0.02% C, strip casted (SC) as well as hot rolled (HR), were thus investigated. The textures were examined by measuring the four incomplete pole figures (110), (200), (112) and (103) in the back reflection mode. The orientation distribution function (ODF) was calculated by the series expansion method (1[sup max]=22). In the case of cubic crystal symmetry and orthorhombic sample symmetry an orientation can then be presented by the three Euler angles [var phi][sub 1], [var phi], [var phi][sub 2] in the reducted Euler space. Since bcc steels tend to develop characteristic fibre textures, it is favorable to present the ODFs as isointensity diagrams in [var phi][sub 1]-sections through the Eulerspace. In this work the [alpha]-fibre and the [gamma]-fibre are of major interest.

  3. Sensitization of stainless steel

    NASA Technical Reports Server (NTRS)

    Nagy, James P.

    1990-01-01

    The objective of this experiment is to determine the corrosion rates of 18-8 stainless steels that have been sensitized at various temperatures and to show the application of phase diagrams. The laboratory instructor will assign each student a temperature, ranging from 550 C to 1050 C, to which the sample will be heated. Further details of the experimental procedure are detailed.

  4. Welding of Stainless Materials

    NASA Technical Reports Server (NTRS)

    Bull, H; Johnson, Lawrence

    1929-01-01

    It would appear that welds in some stainless steels, heat-treated in some practicable way, will probably be found to have all the resistance to corrosion that is required for aircraft. Certainly these structures are not subjected to the severe conditions that are found in chemical plants.

  5. Expendable Pattern Casting Technology

    NASA Astrophysics Data System (ADS)

    1990-07-01

    The expendable pattern casting (EPC) process is a potential casting process breakthrough which could dramatically improve the competitiveness of the U.S. foundry industry. Cooperatively supported by U.S. Industry and the Department of Energy and managed by the American Foundrymen's Society, a project was started in May 1989 to develop and optimize expendable pattern casting technology. Four major tasks were conducted in the first phase of the project. Those tasks involved: (1) reviewing published literature to determine the major problems in the EPC process; (2) evaluating factors influencing sand flow and compaction; (3) evaluating and comparing casting precision obtained in the EPC process with that obtained in other processes; and (4) identifying critical parameters that control dimensional precision and defect formation in EP castings.

  6. Corrosion sensitization behavior and mechanical properties of liquid-nitrogen-deformed austenitic 304 stainless steel

    NASA Astrophysics Data System (ADS)

    Maldonado, Julio Gerardo

    Plastic deformation of 304 stainless steel at liquid nitrogen temperature ({-}196sp°C) produces an almost complete transformation to strain-induced alphasp'/-martensite which provides the necessary conditions for a pseudo-recrystallization of the microstructure. This "so-called" pseudo-recrystallization results directly from the martensitic reversion (i.e. martensite to austenite reverse transformation) upon the application of heat treatment within the sensitization temperature range. The very fine duplex (alpha/gamma) microstructure which results (after heat treatment-0.1h-670sp°C) is also accompanied by a very extensive and homogeneous precipitation of chromium-rich carbides. The concomitant pseudo-recrystallization and precipitation processes not only have a profound positive effect on the sensitization behavior, but also affect the mechanical properties of the material. This suggests that 304 stainless steel could be thermo-mechanically treated, to in essence, heal itself and simultaneously produce an extremely fine (≈0.1mum) duplex grain structure with intermixed carbides to form a very high strength product. This might have important practical implications since 304 stainless steel is the material of choice in many engineering applications. Electrochemical testing, transmission electron microscopy, scanning electron microscopy, optical microscopy, neutron diffraction, X-ray diffraction, and mechanical testing were some of the techniques employed in this work.

  7. The chloride stress-corrosion cracking behavior of stainless steels under different test methods

    SciTech Connect

    Jin, L.Z. . Dept. of Materials Science and Engineering)

    1994-12-01

    Chloride-induced stress-corrosion cracking (SCC) is one of the failure modes of stainless steels. Highly alloyed austenitic stainless steels S32654, S31254, and N08028, and duplex grades S32750 and S31803 possess much improved resistance to SCC compared with S30400 and S31600 steels. With the development of a database, SSData, experimental data collected from calcium chloride tests, autoclave tests, and drop evaporation tests were evaluated. Stress-corrosion cracking data generated by autoclave tests agreed well with the practical service conditions and can be used to discriminate alloys for SCC resistance in sodium chloride solution. Drop evaporation test data can be used in situations where evaporation may occur and cyclic loading may be involved. The SCC resistance of alloys under each method increased with increasing molybdenum equivalent Mo + 0.25Cr + 0.1Ni. For a given alloy, the testing result depends on the stress state and environment; different test methods can give different ranking orders concerning SCC resistance. The performance of duplex stainless steels in a chloride-containing environment at higher temperatures was not as good as expected when dynamic loading was involved.

  8. An atom probe perspective on phase separation and precipitation in duplex stainless steels.

    PubMed

    Guo, Wei; Garfinkel, David A; Tucker, Julie D; Haley, Daniel; Young, George A; Poplawsky, Jonathan D

    2016-06-24

    Three-dimensional chemical imaging of Fe-Cr alloys showing Fe-rich (α)/Cr-rich (α') phase separation is reported using atom probe tomography techniques. The extent of phase separation, i.e., amplitude and wavelength, has been quantitatively assessed using the Langer-Bar-on-Miller, proximity histogram, and autocorrelation function methods for two separate Fe-Cr alloys, designated 2101 and 2205. Although the 2101 alloy possesses a larger wavelength and amplitude after annealing at 427 °C for 100-10 000 h, it exhibits a lower hardness than the 2205 alloy. In addition to this phase separation, ultra-fine Ni-Mn-Si-Cu-rich G-phase precipitates form at the α/α' interfaces in both alloys. For the 2101 alloy, Cu clusters act to form a nucleus, around which a Ni-Mn-Si shell develops during the precipitation process. For the 2205 alloy, the Ni and Cu atoms enrich simultaneously and no core-shell chemical distribution was found. This segregation phenomenon may arise from the exact Ni/Cu ratio inside the ferrite. After annealing for 10 000 h, the number density of the G-phase within the 2205 alloy was found to be roughly one order of magnitude higher than in the 2101 alloy. The G-phase precipitates have an additional deleterious effect on the thermal embrittlement, as evaluated by the Ashby-Orowan equation, which explains the discrepancy between the hardness and the rate of phase separation with respect to annealing time (Gladman T 1999 Mater. Sci. Tech. Ser. 15 30-36). PMID:27181108

  9. An atom probe perspective on phase separation and precipitation in duplex stainless steels

    DOE PAGES

    Garfinkel, David A.; Tucker, Julie D.; Haley, Daniel A.; Young, George A.; Guo, Wei; Poplawsky, Jonathan D.

    2016-05-16

    Here, three-dimensional chemical imaging of Fe–Cr alloys showing Fe-rich (α)/Cr-rich (α') phase separation is reported using atom probe tomography techniques. The extent of phase separation, i.e., amplitude and wavelength, has been quantitatively assessed using the Langer-Bar-on-Miller, proximity histogram, and autocorrelation function methods for two separate Fe–Cr alloys, designated 2101 and 2205. Although the 2101 alloy possesses a larger wavelength and amplitude after annealing at 427 °C for 100–10 000 h, it exhibits a lower hardness than the 2205 alloy. In addition to this phase separation, ultra-fine Ni–Mn–Si–Cu-rich G-phase precipitates form at the α/α' interfaces in both alloys. For the 2101more » alloy, Cu clusters act to form a nucleus, around which a Ni–Mn–Si shell develops during the precipitation process. For the 2205 alloy, the Ni and Cu atoms enrich simultaneously and no core–shell chemical distribution was found. This segregation phenomenon may arise from the exact Ni/Cu ratio inside the ferrite. After annealing for 10 000 h, the number density of the G-phase within the 2205 alloy was found to be roughly one order of magnitude higher than in the 2101 alloy. The G-phase precipitates have an additional deleterious effect on the thermal embrittlement, as evaluated by the Ashby–Orowan equation, which explains the discrepancy between the hardness and the rate of phase separation with respect to annealing time (Gladman T 1999 Mater. Sci. Tech. Ser. 15 30–36).« less

  10. An atom probe perspective on phase separation and precipitation in duplex stainless steels

    NASA Astrophysics Data System (ADS)

    Guo, Wei; Garfinkel, David A.; Tucker, Julie D.; Haley, Daniel; Young, George A.; Poplawsky, Jonathan D.

    2016-06-01

    Three-dimensional chemical imaging of Fe–Cr alloys showing Fe-rich (α)/Cr-rich (α‧) phase separation is reported using atom probe tomography techniques. The extent of phase separation, i.e., amplitude and wavelength, has been quantitatively assessed using the Langer-Bar-on-Miller, proximity histogram, and autocorrelation function methods for two separate Fe–Cr alloys, designated 2101 and 2205. Although the 2101 alloy possesses a larger wavelength and amplitude after annealing at 427 °C for 100–10 000 h, it exhibits a lower hardness than the 2205 alloy. In addition to this phase separation, ultra-fine Ni–Mn–Si–Cu-rich G-phase precipitates form at the α/α‧ interfaces in both alloys. For the 2101 alloy, Cu clusters act to form a nucleus, around which a Ni–Mn–Si shell develops during the precipitation process. For the 2205 alloy, the Ni and Cu atoms enrich simultaneously and no core–shell chemical distribution was found. This segregation phenomenon may arise from the exact Ni/Cu ratio inside the ferrite. After annealing for 10 000 h, the number density of the G-phase within the 2205 alloy was found to be roughly one order of magnitude higher than in the 2101 alloy. The G-phase precipitates have an additional deleterious effect on the thermal embrittlement, as evaluated by the Ashby–Orowan equation, which explains the discrepancy between the hardness and the rate of phase separation with respect to annealing time (Gladman T 1999 Mater. Sci. Tech. Ser. 15 30–36). ).

  11. Kinetic Study to Predict Sigma Phase Formation in Duplex Stainless Steels

    NASA Astrophysics Data System (ADS)

    dos Santos, Daniella Caluscio; Magnabosco, Rodrigo

    2016-04-01

    This work presents an improved kinetic study of sigma phase formation during isothermal aging between 973 K and 1223 K (700 °C and 950 °C), based on Kolmogorov-Johnson-Mehl-Avrami (K-J-M-A) model, established from volume fraction of sigma phase determined in backscattered electron images over polished surfaces of aged samples. The kinetic study shows a change in the main mechanism of sigma formation between 973 K and 1173 K (700 °C and 900 °C), from a nucleation-governed stage to a diffusion-controlled growth-coarsening stage, confirmed by a double inclination in K-J-M-A plots and microstructural observations. A single inclination in K-J-M-A plots was observed for the 1223 K (950 °C) aging temperature, showing that kinetic behavior in this temperature is only related to diffusion-controlled growth of sigma phase. The estimated activation energies for the nucleation of sigma phase are close to the molybdenum diffusion in ferrite, probably the controlling mechanism of sigma phase nucleation. The proposed time-temperature-transformation (TTT) diagram shows a "double c curve" configuration, probably associated to the presence of chi-phase formed between 973 K and 1073 K (700 °C and 800 °C), which acts as heterogeneous nuclei for sigma phase formation in low aging temperatures.

  12. An atom probe perspective on phase separation and precipitation in duplex stainless steels

    NASA Astrophysics Data System (ADS)

    Guo, Wei; Garfinkel, David A.; Tucker, Julie D.; Haley, Daniel; Young, George A.; Poplawsky, Jonathan D.

    2016-06-01

    Three-dimensional chemical imaging of Fe-Cr alloys showing Fe-rich (α)/Cr-rich (α‧) phase separation is reported using atom probe tomography techniques. The extent of phase separation, i.e., amplitude and wavelength, has been quantitatively assessed using the Langer-Bar-on-Miller, proximity histogram, and autocorrelation function methods for two separate Fe-Cr alloys, designated 2101 and 2205. Although the 2101 alloy possesses a larger wavelength and amplitude after annealing at 427 °C for 100-10 000 h, it exhibits a lower hardness than the 2205 alloy. In addition to this phase separation, ultra-fine Ni-Mn-Si-Cu-rich G-phase precipitates form at the α/α‧ interfaces in both alloys. For the 2101 alloy, Cu clusters act to form a nucleus, around which a Ni-Mn-Si shell develops during the precipitation process. For the 2205 alloy, the Ni and Cu atoms enrich simultaneously and no core-shell chemical distribution was found. This segregation phenomenon may arise from the exact Ni/Cu ratio inside the ferrite. After annealing for 10 000 h, the number density of the G-phase within the 2205 alloy was found to be roughly one order of magnitude higher than in the 2101 alloy. The G-phase precipitates have an additional deleterious effect on the thermal embrittlement, as evaluated by the Ashby-Orowan equation, which explains the discrepancy between the hardness and the rate of phase separation with respect to annealing time (Gladman T 1999 Mater. Sci. Tech. Ser. 15 30-36). ).

  13. Clean Metal Casting

    SciTech Connect

    Makhlouf M. Makhlouf; Diran Apelian

    2002-02-05

    The objective of this project is to develop a technology for clean metal processing that is capable of consistently providing a metal cleanliness level that is fit for a given application. The program has five tasks: Development of melt cleanliness assessment technology, development of melt contamination avoidance technology, development of high temperature phase separation technology, establishment of a correlation between the level of melt cleanliness and as cast mechanical properties, and transfer of technology to the industrial sector. Within the context of the first task, WPI has developed a standardized Reduced Pressure Test that has been endorsed by AFS as a recommended practice. In addition, within the context of task1, WPI has developed a melt cleanliness sensor based on the principles of electromagnetic separation. An industrial partner is commercializing the sensor. Within the context of the second task, WPI has developed environmentally friendly fluxes that do not contain fluorine. Within the context of the third task, WPI modeled the process of rotary degassing and verified the model predictions with experimental data. This model may be used to optimize the performance of industrial rotary degassers. Within the context of the fourth task, WPI has correlated the level of melt cleanliness at various foundries, including a sand casting foundry, a permanent mold casting foundry, and a die casting foundry, to the casting process and the resultant mechanical properties. This is useful in tailoring the melt cleansing operations at foundries to the particular casting process and the desired properties of cast components.

  14. Ultrasound treatment of centrifugally atomized 316 stainless steel powders

    NASA Astrophysics Data System (ADS)

    Rawers, James C.; McCune, Robert A.; Dunning, John S.

    1991-12-01

    The Bureau of Mines is studying the surface characteristics of rapidly solidified powders and the potential for surface modification of fine powders prior to consolidation. The surface modification and work hardening of fine powders were accomplished by applying high-energy ultrasound to centrifugally atomized austenitic 316 stainless steel powders suspended in liquid media. Cavitation implosion changed the surface morphology, hammering the surface and occasionally fretting off microchips of work-hardened metal. Ultrasound-cavitation work-hardened metal powder surfaces producing a strained, duplex austenite face-centered cubic (fcc)-martensite body-centered tetragonal (bct) phase structure. The amount of work hardening depended upon the quantity of ultrasound energy used, considering both power level and experimental time. Work hardening was relatively independent of the liquid media used.

  15. INTERIOR VIEW WITH LARGE PIPE CASTING MACHINE CASTING A 48' ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW WITH LARGE PIPE CASTING MACHINE CASTING A 48' PIPE OPERATOR SPRAYING A POWDER TO HELP SOLIDIFY THE PIPE BEING CENTRIFUGALLY CAST. - United States Pipe & Foundry Company Plant, Pipe Casting & Testing Area, 2023 St. Louis Avenue at I-20/59, Bessemer, Jefferson County, AL

  16. Streamlined analysis of duplex sequencing data with Du Novo.

    PubMed

    Stoler, Nicholas; Arbeithuber, Barbara; Guiblet, Wilfried; Makova, Kateryna D; Nekrutenko, Anton

    2016-01-01

    Duplex sequencing was originally developed to detect rare nucleotide polymorphisms normally obscured by the noise of high-throughput sequencing. Here we describe a new, streamlined, reference-free approach for the analysis of duplex sequencing data. We show the approach performs well on simulated data and precisely reproduces previously published results and apply it to a newly produced dataset, enabling us to type low-frequency variants in human mitochondrial DNA. Finally, we provide all necessary tools as stand-alone components as well as integrate them into the Galaxy platform. All analyses performed in this manuscript can be repeated exactly as described at http://usegalaxy.org/duplex . PMID:27566673

  17. Streamlined analysis of duplex sequencing data with Du Novo.

    PubMed

    Stoler, Nicholas; Arbeithuber, Barbara; Guiblet, Wilfried; Makova, Kateryna D; Nekrutenko, Anton

    2016-08-26

    Duplex sequencing was originally developed to detect rare nucleotide polymorphisms normally obscured by the noise of high-throughput sequencing. Here we describe a new, streamlined, reference-free approach for the analysis of duplex sequencing data. We show the approach performs well on simulated data and precisely reproduces previously published results and apply it to a newly produced dataset, enabling us to type low-frequency variants in human mitochondrial DNA. Finally, we provide all necessary tools as stand-alone components as well as integrate them into the Galaxy platform. All analyses performed in this manuscript can be repeated exactly as described at http://usegalaxy.org/duplex .

  18. Lubrication for high load duplex bearings

    SciTech Connect

    Steinhoff, R.G.

    1997-08-01

    Three ES and H-compatible lubricants (Environment, Safety and Health) for high load duplex bearing applications were evaluated and compared against trichlorotrifluoroethane (Freon) deposition of low molecular weight polytetrafluoroethylene (PTFE) bearing lubricant extracted from Vydax{trademark}. Vydax is a product manufactured by DuPont consisting of various molecular weights of PTFE suspended in trichlorotrifluoroethane (Freon) which is an ozone-depleting solvent. Bearings with Supercritical CO{sub 2} deposition of PTFE extracted from Vydax AR/IPA, bearings with titanium carbide coated balls, and bearings with diamond-like carbon races and retainers were evaluated. Bearings with Supercritical CO{sub 2} deposition of PTFE from Vydax AR/IPA performed as well as bearings with Freon deposition of PTFE from Freon-based Vydax.

  19. Fatigue crack propagation behavior of stainless steel welds

    NASA Astrophysics Data System (ADS)

    Kusko, Chad S.

    The fatigue crack propagation behavior of austenitic and duplex stainless steel base and weld metals has been investigated using various fatigue crack growth test procedures, ferrite measurement techniques, light optical microscopy, stereomicroscopy, scanning electron microscopy, and optical profilometry. The compliance offset method has been incorporated to measure crack closure during testing in order to determine a stress ratio at which such closure is overcome. Based on this method, an empirically determined stress ratio of 0.60 has been shown to be very successful in overcoming crack closure for all da/dN for gas metal arc and laser welds. This empirically-determined stress ratio of 0.60 has been applied to testing of stainless steel base metal and weld metal to understand the influence of microstructure. Regarding the base metal investigation, for 316L and AL6XN base metals, grain size and grain plus twin size have been shown to influence resulting crack growth behavior. The cyclic plastic zone size model has been applied to accurately model crack growth behavior for austenitic stainless steels when the average grain plus twin size is considered. Additionally, the effect of the tortuous crack paths observed for the larger grain size base metals can be explained by a literature model for crack deflection. Constant Delta K testing has been used to characterize the crack growth behavior across various regions of the gas metal arc and laser welds at the empirically determined stress ratio of 0.60. Despite an extensive range of stainless steel weld metal FN and delta-ferrite morphologies, neither delta-ferrite morphology significantly influence the room temperature crack growth behavior. However, variations in weld metal da/dN can be explained by local surface roughness resulting from large columnar grains and tortuous crack paths in the weld metal.

  20. Symptomatic stent cast.

    PubMed

    Keohane, John; Moore, Michael; O'Mahony, Seamus; Crosbie, Orla

    2008-02-01

    Biliary stent occlusion is a major complication of endoscopic stent insertion and results in repeat procedures. Various theories as to the etiology have been proposed, the most frequently studied is the attachment of gram negative bacteria within the stent. Several studies have shown prolongation of stent patency with antibiotic prophylaxis. We report the case of stent occlusion from a cast of a previously inserted straight biliary stent; a "stent cast" in an 86-year-old woman with obstructive jaundice. This was retrieved with the lithotrypter and she made an uneventful recovery. This is the first reported case of a biliary stent cast.

  1. CASTING METHOD AND APPARATUS

    DOEpatents

    Gray, C.F.; Thompson, R.H.

    1958-10-01

    An improved apparatus for the melting and casting of uranium is described. A vacuum chamber is positioned over the casting mold and connected thereto, and a rod to pierce the oxide skin of the molten uranium is fitted into the bottom of the melting chamber. The entire apparatus is surrounded by a jacket, and operations are conducted under a vacuum. The improvement in this apparatus lies in the fact that the top of the melting chamber is fitted with a plunger which allows squeezing of the oxide skin to force out any molten uranium remaining after the skin has been broken and the molten charge has been cast.

  2. CENTRIFUGAL CASTING MACHINE

    DOEpatents

    Shuck, A.B.

    1958-04-01

    A device is described that is specifically designed to cast uraniumn fuel rods in a vacuunn, in order to obtain flawless, nonoxidized castings which subsequently require a maximum of machining or wastage of the expensive processed material. A chamber surrounded with heating elements is connected to the molds, and the entire apparatus is housed in an airtight container. A charge of uranium is placed in the chamber, heated, then is allowed to flow into the molds While being rotated. Water circulating through passages in the molds chills the casting to form a fine grained fuel rod in nearly finished form.

  3. Thermoacoustic Duplex Technology for Cooling and Powering a Venus Lander

    NASA Astrophysics Data System (ADS)

    Walker, A. R.; Haberbusch, M. S.; Sasson, J.

    2015-04-01

    A Thermoacoustic Stirling Heat Engine (TASHE) is directly coupled to a Pulse Tube Refrigerator (PTR) in a duplex configuration, providing simultaneous cooling and electrical power, thereby suiting the needs of a long-lived Venus lander.

  4. 43. View of station from southwest side with duplex keepers' ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    43. View of station from southwest side with duplex keepers' dwelling to the left. USLHB photo by Herbert Bamber, June 9, 1893. - Bodie Island Light Station, Off Highway 12, Nags Head, Dare County, NC

  5. Casting Characteristics of Aluminum Die Casting Alloys

    SciTech Connect

    Makhlouf M. Makhlouf; Diran Apelian

    2002-02-05

    The research program investigates the casting characteristics of selected aluminum die casting alloys. Specifically, the alloys' tendencies towards die soldering and sludge formation, and the alloys' fluidity and machinability are evaluated. It was found that: When the Fe and Mn contents of the alloy are low; caution has to be taken against possible die soldering. When the alloy has a high sludge factor, particularly a high level of Fe, measures must be taken to prevent the formation of large hardspots. For this kind of alloy, the Fe content should be kept at its lowest allowable level and the Mn content should be at its highest possible level. If there are problems in die filling, measures other than changing the alloy chemistry need to be considered first. In terms of alloy chemistry, the elements that form high temperature compounds must be kept at their lowest allowable levels. The alloys should not have machining problems when appropriate machining techniques and machining parameters are used.

  6. Method of casting aerogels

    SciTech Connect

    Poco, J.F.

    1993-09-07

    The invention describes a method for making monolithic castings of transparent silica aerogel with densities in the range from 0.001 g/cm[sup 3] to 0.6 g/cm[sup 3]. Various shapes of aerogels are cast in flexible polymer molds which facilitate removal and eliminate irregular surfaces. Mold dimensions are preselected to account for shrinkage of aerogel which occurs during the drying step of supercritical extraction of solvent. 2 figures.

  7. MOLDS FOR CASTING PLUTONIUM

    DOEpatents

    Anderson, J.W.; Miley, F.; Pritchard, W.C.

    1962-02-27

    A coated mold for casting plutonium comprises a mold base portion of a material which remains solid and stable at temperatures as high as the pouring temperature of the metal to be cast and having a thin coating of the order of 0.005 inch thick on the interior thereof. The coating is composed of finely divided calcium fluoride having a particle size of about 149 microns. (AEC)

  8. Method of casting aerogels

    DOEpatents

    Poco, John F.

    1993-01-01

    The invention describes a method for making monolithic castings of transparent silica aerogel with densities in the range from 0.001 g/cm.sup.3 to 0.6 g/cm.sup.3. Various shapes of aerogels are cast in flexible polymer molds which facilitate removal and eliminate irregular surfaces. Mold dimensions are preselected to account for shrinkage of alcogel which occurs during the drying step of supercritical extraction of solvent.

  9. A Winning Cast

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Howmet Research Corporation was the first to commercialize an innovative cast metal technology developed at Auburn University, Auburn, Alabama. With funding assistance from NASA's Marshall Space Flight Center, Auburn University's Solidification Design Center (a NASA Commercial Space Center), developed accurate nickel-based superalloy data for casting molten metals. Through a contract agreement, Howmet used the data to develop computer model predictions of molten metals and molding materials in cast metal manufacturing. Howmet Metal Mold (HMM), part of Howmet Corporation Specialty Products, of Whitehall, Michigan, utilizes metal molds to manufacture net shape castings in various alloys and amorphous metal (metallic glass). By implementing the thermophysical property data from by Auburn researchers, Howmet employs its newly developed computer model predictions to offer customers high-quality, low-cost, products with significantly improved mechanical properties. Components fabricated with this new process replace components originally made from forgings or billet. Compared with products manufactured through traditional casting methods, Howmet's computer-modeled castings come out on top.

  10. Perspective view of Building No. 61 from northwest. These duplex ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Perspective view of Building No. 61 from northwest. These duplex quarters were built during the 1920s on the south edge of the Northwestern Branch campus. This building is sited on a rise and shares paths and lawn with two similar structures - Buildings 56 and 79. Now located directly adjacent to the current hospital complex (background), all three duplexes are slated for demolition. - National Home for Disabled Volunteer Soldiers, Northwestern Branch, Quarters, 5000 West National Avenue, Milwaukee, Milwaukee County, WI

  11. Salvaged castings and methods of salvaging castings with defective cast cooling bumps

    DOEpatents

    Johnson, Robert Alan; Schaeffer, Jon Conrad; Lee, Ching-Pang; Abuaf, Nesim; Hasz, Wayne Charles

    2002-01-01

    Castings for gas turbine parts exposed on one side to a high-temperature fluid medium have cast-in bumps on an opposite cooling surface side to enhance heat transfer. Areas on the cooling surface having defectively cast bumps, i.e., missing or partially formed bumps during casting, are coated with a braze alloy and cooling enhancement material to salvage the part.

  12. Through process numerical simulation of a heavy hydro turbine blade casting

    NASA Astrophysics Data System (ADS)

    Kang, J. W.; Wang, T. J.; Y Huang, T.; Liu, B. C.

    2012-07-01

    Heavy Hydro turbine castings, made of martensitic stainless steel, of spatially twisted shape, are susceptible to deformation during both casting and heat treatment processes. During production, uneven heating and cooling, phase transformation, stress and stain are responsible for the deformation of castings. However, the current research most focus on casting process or heat treatment process or both but separately, martensitic phase transformation is usually neglected in casting process. In this paper, a coupled thermo-martensitic phase transformation-stress model is established. And it is implemented by secondary development of ABAQUS, which deals the finite element model change and incorporates multi thermal and mechanical boundaries during casting and heat treatment processes as well, such as the contact pair between casting and mold during casting process. The stress analysis of a heavy hydro blade casting was performed by this system. The stress, displacement and phase are obtained. The effect of martensitic phase transformation on the stress and deformation is discussed. The simulated deformation is compared with measured results, and their agreement is improved by the through process simulation.

  13. Metal Penetration in Sand Molds for Steel Castings: Annual Report

    SciTech Connect

    Barlow, J.O.; Stefanescu, D.M.; Lane, A.M.; Schreiber, W.C.; Owens, M.; Piwonka, T.S.

    1996-04-01

    Case studies of samples of penetration provided by consortium members showed examples of mechanical-type penetration defects and of what appeared to be chemical penetration. Sessile drop experiments of various mold substrate materials using carbon, stainless, and Mn steels showed that Mn steel wets silica strongly, indicating that silica is not a suitable mod material for this family of alloys. Contact angles were lower for steels than for cast irons. Magnesite appeared to be the best overall mold material, although zircon flour also performed well. A simplified 1-D model was developed which predicts the diffusion rates which could cause chemical penetration. It shows that, contrary to the case in cast iron, chemical penetration is a possibility in medium and low carbon steels, as diffusion of C to the casting surface may not always occur quickly enough to protect the surface from an oxidizing reaction. The mass spectrometer gas chromatograph train was modified for accurately determining the water content of gas at the mold/metal interface. Initial gas measurements indicated that the gas generated at the interface in steel castings is 80% H2-20% CO, instead of the 50% H2- 50% CO mixture found in cast iron.

  14. Topologically non-linked circular duplex DNA.

    PubMed

    Biegeleisen, Ken

    2002-05-01

    The discovery of circular DNA, over 30 years ago, introduced an element of uneasiness in what had been, up to that point, the almost picture-perfect story of the elucidation of the molecular biology of heredity. If DNA indeed has the Watson-Crick right-handed helical secondary structure, then in circular DNA, thousands, or perhaps even millions of twists must be removed in each generation, and re-wound in the next generation. Although enzyme systems adequate for this task have long since been found and characterized, there have nevertheless arisen a number of proposals for alternative DNA structures in which the strands are topologically non-linked, so that they might separate during replication without having to be unwound. These structures have generally been put forth as theory only, and have been largely unaccompanied by experimental evidence to support their applicability to native DNA from living systems. Recently, however, a report has emerged suggesting that it might be possible to separate, intact, the individual single-stranded circular half-chromosomes which constitute the double-stranded circular chromosomes of certain plasmids. This would not be possible unless the chromosomes had one of the alternative, topologically non-linked structures. It is widely believed that after a half-century of worldwide DNA research, any significant change to the Watson-Crick structure is unlikely to stand up to scrutiny. Nevertheless, the present author has found that in many instances in which the behavior of circular duplex DNA is considered to be explicable only in terms of the topologically linked helical model, it is also possible to explain that same behavior in terms of a topologically non-linked model. It is necessary, in these instances, to make certain logical assumptions which cannot be conclusively proven at the present time. The author herein offers an example of one such instance, namely an examination of the behavior of circular duplex DNA in an alkaline

  15. Solidification behavior and microstructural analysis of austenitic stainless steel laser welds

    SciTech Connect

    David, S.A.; Vitek, J.M.

    1981-01-01

    Solidification behavior of austenitic stainless steel laser welds has been investigated with a high-power laser system. The welds were made at speeds ranging from 13 to 60 mm/s. The welds sowed a wide variety of microstructural features. The ferrite content in the 13-mm/s weld varied from less than 1% at the root of the weld to about 10% at the crown. The duplex structure at the crown of the weld was much finer than the one observed in conventional weld metal. However, the welds made at 25 and 60 mm/s contained an austenitic structure with less than 1% ferrite throughout the weld. Microstructural analysis of these welds used optical microscopy, transmission electron microscopy, and analytical electron microscopy. The austenitic stainless steel welds were free of any cracking, and the results are explained in terms of the rapid solidification conditions during laser welding.

  16. MIC on stainless steels in wastewater treatment plants

    SciTech Connect

    Iversen, A.

    1999-11-01

    Field tests of stainless steels were carried out at five wastewater treatment plants for one year. Three stainless steel grades i.e. AISI 304 (UNS S30400), AISI 316 (UNS S31600) and duplex 2205 (UNS S31803) were tested in the final settling tank in the plants. The time dependence of the open circuit potential (OCP) was measured for all coupons. Ennoblement of the OCP, similar to that reported from investigations in seawater, was found in one of the plants. Waters from three of the exposure sites, containing dispersed deposits from exposed coupons, were chemically analyzed. Pitting corrosion was observed after the field test on steel grade AISI 304 in three of the five plants, and on AISI 316 in one plant. No corrosion was found on 2205 in any of the plants. Laboratory measurements of the OCP were carried out for AISI 304, AISI 316 and 2205 in water collected from one of the plants. Cathodic polarization curves were determined as well in wastewater from the same plant. The cathodic reaction rate increased at the highest OCP. Simulation of the ennoblement was carried out by potentiostatic polarization in a 600 ppm chloride solution. The current response indicated corrosion on AISI 304 welded material and on AISI 304, AISI 316 in crevice assemblies after a long period of induction time.

  17. ES and H-compatible lubrication for duplex bearings

    SciTech Connect

    Steinhoff, R.G.

    1997-10-01

    Two ES and H-compatible lubricants (environment, safety, and health) for duplex bearing applications and one hybrid material duplex bearing were evaluated and compared against duplex bearings with trichlorotrifluoroethane (Freon) deposition of low molecular weight polytetrafluoroethylene (PTFE) bearing lubricant extracted from Vydax{trademark}. Vydax is a product manufactured by DuPont consisting of various molecular weights of PTFE suspended in trichlorotrifluoroethane (Freon), which is an ozone-depleting solvent. Vydax has been used as a bearing lubricant in strong link mechanisms since 1974. Hybrid duplex bearings with silicon nitride balls and molded glass-nylon-Teflon retainers, duplex bearings lubricated with sputtered MoS{sub 2} on races and retainers, and duplex bearings lubricated with electrophoretic deposited MoS{sub 2} were evaluated. Bearings with electrophoretic deposited MoS{sub 2} performed as well as bearings with Freon deposition of PTFE from Freon-based Vydax. Hybrid bearings with silicon nitride balls performed worse than bearings lubricated with Vydax, but their performance would still be acceptable for most applications. Bearings lubricated with sputtered MoS{sub 2} on the races and retainers had varying amounts of film on the bearings. This affected the performance of the bearings. Bearings with a uniform coating performed to acceptable levels, but bearings with no visible MoS{sub 2} on the races and retainers did not perform as well as bearings with the other coatings. Unless process controls are incorporated in the sputtering process or the bearings are screened, they do not appear to be acceptable for duplex bearing applications.

  18. Development of Low-Cost Austenitic Stainless Gas-Turbine and Diesel Engine Components with Enhanced High-Temperature Reliability

    SciTech Connect

    Maziasz, P.J.; Swindeman, R.W.; Browning, P.F.; Frary, M.E.; Pollard, M.J.; Siebenaler, C.W.; McGreevy, T.E.

    2004-06-01

    In July of 1999, a Cooperative Research and Development Agreement (CRADA) was undertaken between Oak Ridge National Laboratory (ORNL) and Solar Turbines, Inc. and Caterpillar, Inc. (Caterpillar Technical Center) to evaluate commercial cast stainless steels for gas turbine engine and diesel engine exhaust component applications relative to the materials currently being used. If appropriate, the goal was to develop cast stainless steels with improved performance and reliability rather than switch to more costly cast Ni-based superalloys for upgraded performance. The gas-turbine components considered for the Mercury-50 engine were the combustor housing and end-cover, and the center-frame hot-plate, both made from commercial CF8C cast austenitic stainless steel (Fe-l9Cr-12Ni-Nb,C), which is generally limited to use at below 650 C. The advanced diesel engine components considered for truck applications (C10, C12, 3300 and 3400) were the exhaust manifold and turbocharger housing made from commercial high SiMo ductile cast iron with uses limited to 700-750 C or below. Shortly after the start of the CRADA, the turbine materials emphasis changed to wrought 347H stainless steel (hot-plate) and after some initial baseline tensile and creep testing, it was confirmed that this material was typical of those comprising the abundant database; and by 2000, the emphasis of the CRADA was primarily on diesel engine materials. For the diesel applications, commercial SiMo cast iron and standard cast CN12 austenitic stainless steel (Fe-25Cr-13Ni-Nb,C,N,S) baseline materials were obtained commercially. Tensile and creep testing from room temperature to 900 C showed the CN12 austenitic stainless steel to have far superior strength compared to SiMo cast iron above 550 C, together with outstanding oxidation resistance. However, aging at 850 C reduced room-temperature ductility of the standard CN12, and creep-rupture resistance at 850 C was less than expected, which triggered a focused

  19. Fracture during cooling of cast borosilicate glass containing nuclear wastes

    SciTech Connect

    Smith, P.K.; Baxter, C.A.

    1981-09-01

    Procedures and techniques were evaluated to mitigate thermal stress fracture in waste glass as the glass cools after casting. The two principal causes of fracture identified in small-scale testing are internal thermal stresses arising from excessive thermal gradients when cooled too fast, and shear fracturing in the surface of the glass because the stainless steel canister shrinks faster than the glass on cooling. Acoustic emission and ceramographic techniques were used to outline an annealing schedule that requires at least three weeks of controlled cooling below 550/sup 0/C to avoid excessive thermal gradients and corresponding stresses. Fracture arising from canister interactions cannot be relieved by slow cooling, but can be eliminated for stainless steel canisters by using ceramic paper, ceramic or graphite paste linings, or by choosing a canister material with a thermal expansion coefficient comparable to, or less than, that of the glass.

  20. CAST FLOOR WITH VIEW OF TORPEDO LADLE (BENEATH CAST FLOOR) ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CAST FLOOR WITH VIEW OF TORPEDO LADLE (BENEATH CAST FLOOR) AND KEEPERS OF THE CAST HOUSE FLOOR, S.L. KIMBROUGH AND DAVID HOLMES. - U.S. Steel, Fairfield Works, Blast Furnace No. 8, North of Valley Road, West of Ensley-Pleasant Grove Road, Fairfield, Jefferson County, AL

  1. Duplex Ultrasonography in Assessing Restenosis of Renal Artery Stents

    SciTech Connect

    Bakker, Jeannette; Beutler, Jaap J.; Elgersma, Otto E.H.; Lange, Eduard E. de; Kort, Gerard A.P. de; Beek, Frederik J. A.

    1999-11-15

    Purpose: To determine the accuracy and optimal threshold values of duplex ultrasonography (US) in assessing restenosis of renal artery stents. Methods: Twenty-four consecutive patients with 33 renal arteries that had previously been treated with placement of a Palmaz stent underwent duplex US prior to intraarterial digital subtraction angiography (DSA), which was the reference standard. Diagnostic accuracy of in-stent peak systolic velocity (PSV) and reno-aortic ratio (RAR = PSV renal stent/PSV aorta) in detecting > 50% in-stent restenosis were evaluated by the receiver operating characteristic curve. Sensitivity and specificity were determined using the optimal threshold values, and using published threshold values: RAR > 3.5 and in-stent PSV > 180 cm/sec. Results: Six examinations were technically inadequate. Nine stents had residual or restenosis > 50% at DSA. The two duplex parameters were equally accurate since areas under the curves were similar (0.943). With optimal threshold values of 226 cm/sec for PSV and 2.7 for RAR, sensitivities and specificities were 100% and 90%, and 100% and 84%, respectively. Using the published duplex criteria resulted in sensitivities and specificities of 100% and 74% for PSV, and 50% and 89% for RAR. Conclusion: Duplex US is a sensitive modality for detecting in-stent restenosis if laboratory-specific threshold values are used.

  2. Method for casting polyethylene pipe

    NASA Technical Reports Server (NTRS)

    Elam, R. M., Jr.

    1973-01-01

    Short lengths of 7-cm ID polyethylene pipe are cast in a mold which has a core made of room-temperature-vulcanizable (RTV) silicone. Core expands during casting and shrinks on cooling to allow for contraction of the polyethylene.

  3. Casting Of Multilayer Ceramic Tapes

    NASA Technical Reports Server (NTRS)

    Collins, Earl R., Jr.

    1991-01-01

    Procedure for casting thin, multilayer ceramic membranes, commonly called tapes, involves centrifugal casting at accelerations of 1,800 to 2,000 times normal gravitational acceleration. Layers of tape cast one at a time on top of any previous layer or layers. Each layer cast from slurry of ground ceramic suspended in mixture of solvents, binders, and other components. Used in capacitors, fuel cells, and electrolytic separation of oxygen from air.

  4. Comparative evaluation of retention of prefabricated and conventional cast post: An in vitro study

    PubMed Central

    Choudhary, Suchismita; Begum, Zubeda; Choudhary, Prashant; Tripathi, Siddhi

    2014-01-01

    Background and Objectives: This study was conducted to evaluate the retention of various prefabricated posts and to compare them with that of the conventional cast post. Materials and Methods: A sample of 60 freshly extracted single-rooted human mandibular first premolars were sectioned horizontally, 1 mm coronal to the cemento-enamel junction and randomly divided into four groups consisting of carbon fiber posts, glass fiber posts, stainless steel posts and cast metal posts. Cast metal post was the control group. Each group contained 15 specimen. The post space of 9 mm depth was prepared using specific drill supplied by the manufacturer. Resin patterns of the prepared post spaces were fabricated for 15 specimen and were cast in nickel chromium base metal alloy. All the posts were cemented with self-adhesive resin cement and mounted in acrylic cylinders. The teeth were subjected to tensile pull-out test using a universal testing machine. The force required to dislodge each post from the teeth was recorded. The data was analyzed using one-way analysis of variance and Bonferroni test. Results: The bond strength of all the prefabricated posts was significantly lower than the conventional cast post. Among the prefabricated posts highest bond strength was obtained for prefabricated stainless steel post and lowest for carbon fiber posts. There was no significant difference in the mean bond strength obtained for stainless steel and glass fiber post. Conclusion: Though no single prefabricated post could achieve results close to the control group, most retentive among the experimental group were the stainless steel posts. However, conditions where nonmetallic posts are indicated most preferred type of post can be the glass fiber posts. PMID:25254191

  5. Theoretical studies of d(A:T)-based parallel-stranded DNA duplexes.

    PubMed

    Cubero, E; Luque, F J; Orozco, M

    2001-12-01

    Poly d(A:T) parallel-stranded DNA duplexes based on the Hoogsteen and reverse Watson-Crick hydrogen bond pairing are studied by means of extensive molecular dynamics (MD) simulations and molecular mechanics coupled to Poisson-Boltzmann (MM-PB/SA) calculations. The structural, flexibility, and reactivity characteristics of Hoogsteen and reverse Watson-Crick parallel duplexes are described from the analysis of the trajectories. Theoretical calculations show that the two parallel duplexes are less stable than the antiparallel Watson-Crick duplex. The difference in stability between antiparallel and parallel duplexes increases steadily as the length of the duplex increases. The reverse Watson-Crick arrangement is slightly more stable than the Hoogsteen duplex, the difference being also increased linearly with the length of the duplex. A subtle balance of intramolecular and solvation terms is responsible for the preference of a given helical structure.

  6. Surface modification of investment cast-316L implants: microstructure effects.

    PubMed

    El-Hadad, Shimaa; Khalifa, Waleed; Nofal, Adel

    2015-03-01

    Artificial femur stem of 316L stainless steel was fabricated by investment casting using vacuum induction melting. Different surface treatments: mechanical polishing, thermal oxidation and immersion in alkaline solution were applied. Thicker hydroxyapatite (HAP) layer was formed in the furnace-oxidized samples as compared to the mechanically polished ones. The alkaline treatment enhanced the precipitation of HAP on the samples. It was also observed that the HAP precipitation responded differently to the different phases of the microstructure. The austenite phase was observed to have more homogeneous and smoother layer of HAP. In addition, the growth of HAP was sometimes favored on the austenite phase rather than on ferrite phase.

  7. Casting and Angling.

    ERIC Educational Resources Information Center

    Smith, Julian W.

    As part of a series of books and pamphlets on outdoor education, this manual consists of easy-to-follow instructions for fishing activities dealing with casting and angling. The manual may be used as a part of the regular physical education program in schools and colleges or as a club activity for the accomplished weekend fisherman or the…

  8. Extrusion cast explosive

    DOEpatents

    Scribner, Kenneth J.

    1985-01-01

    Improved, multiphase, high performance, high energy, extrusion cast explosive compositions, comprising, a crystalline explosive material; an energetic liquid plasticizer; a urethane prepolymer, comprising a blend of polyvinyl formal, and polycaprolactone; a polyfunctional isocyanate; and a catalyst are disclosed. These new explosive compositions exhibit higher explosive content, a smooth detonation front, excellent stability over long periods of storage, and lower sensitivity to mechanical stimulants.

  9. ShakeCast Manual

    USGS Publications Warehouse

    Lin, Kuo-Wan; Wald, David J.

    2008-01-01

    ShakeCast is a freely available, post-earthquake situational awareness application that automatically retrieves earthquake shaking data from ShakeMap, compares intensity measures against users? facilities, and generates potential damage assessment notifications, facility damage maps, and other Web-based products for emergency managers and responders.

  10. Mix/Cast Contamination Control

    NASA Technical Reports Server (NTRS)

    Wallentine, M.

    2005-01-01

    Presented is a training handbook for Mix/Cast Contamination Control; a part of a series of training courses to qualify access to Mix/Cast facilities. Contents: List Contamination Control Requirements; Identify foreign objects debris (FOD), Control Areas and their guidelines; Describe environmental monitoring; List Contamination Control Initiatives; Describe concern for Controlled Materials; Identify FOD Controlled Areas in Mix/Cast.

  11. Defined presentation of carbohydrates on a duplex DNA scaffold.

    PubMed

    Schlegel, Mark K; Hütter, Julia; Eriksson, Magdalena; Lepenies, Bernd; Seeberger, Peter H

    2011-12-16

    A new method for the spatially defined alignment of carbohydrates on a duplex DNA scaffold is presented. The use of an N-hydroxysuccinimide (NHS)-ester phosphoramidite along with carbohydrates containing an alkylamine linker allows for on-column labeling during solid-phase oligonucleotide synthesis. This modification method during solid-phase synthesis only requires the use of minimal amounts of complex carbohydrates. The covalently attached carbohydrates are presented in the major groove of the B-form duplex DNA as potential substrates for murine type II C-type lectin receptors mMGL1 and mMGL2. CD spectroscopy and thermal melting revealed only minimal disturbance of the overall helical structure. Surface plasmon resonance and cellular uptake studies with bone-marrow-derived dendritic cells were used to assess the capability of these carbohydrate-modified duplexes to bind to mMGL receptors.

  12. Welding tritium exposed stainless steel

    SciTech Connect

    Kanne, W.R. Jr.

    1994-11-01

    Stainless steels that are exposed to tritium become unweldable by conventional methods due to buildup of decay helium within the metal matrix. With longer service lives expected for tritium containment systems, methods for welding on tritium exposed material will become important for repair or modification of the systems. Solid-state resistance welding and low-penetration overlay welding have been shown to mitigate helium embrittlement cracking in tritium exposed 304 stainless steel. These processes can also be used on stainless steel containing helium from neutron irradiation, such as occurs in nuclear reactors.

  13. Evaluation of cast carbon steel and aluminum for rack insert in MCO Mark 1A fuel basket

    SciTech Connect

    Graves, C.E., Fluor Daniel Hanford

    1997-03-21

    This document evaluates the effects ofusing a cast carbon steel or aluminum instead of 3O4L stainless steel in the construction ofthe fuel rack insert for the Spent Nuclear Fuel MCO Mark IA fuel baskets. The corrosion, structural, and cost effects are examined.

  14. Unique Dynamic Properties of DNA Duplexes Containing Interstrand Crosslinks†

    PubMed Central

    Friedman, Joshua I.; Jiang, Yu Lin; Miller, Paul S.; Stivers, James T.

    2010-01-01

    Bifunctional DNA alkylating agents form a diverse assortment of covalent DNA interstrand crosslinked (ICL) structures that are potent cytotoxins. Since it is implausible that cells could possess distinct DNA repair systems for each individual ICL, it is believed that common structural and dynamic features of ICL damage are recognized, rather than specific structural characteristics of each cross-linking agent. Investigation of the structural and dynamic properties of ICLs that might be important for recognition has been complicated by heterogeneous incorporation of these lesions into DNA. To address this problem we have synthesized and characterized several homogenous ICL-DNAs containing site–specific staggered N4-cytosine-ethyl-N4-cytosine crosslinks. Staggered crosslinks were introduced in two ways: in a manner that preserves the overall structure of B-form duplex DNA, and in a manner that highly distorts the DNA structure, with the goal of understanding how structural and dynamic properties of diverse ICL duplexes might flag these sites for repair. Measurements of base pair opening dynamics in the B-form ICL duplex by 1H NMR linewidth or imino proton solvent exchange showed that the guanine base opposite to the crosslinked cytosine opened at least an order of magnitude more slowly than when in a control matched normal duplex. To a lesser degree, the B-form ICL also induced a decrease in base pair opening dynamics that extended from the site of the crosslink to adjacent base pairs. In contrast, the non-B-form ICL showed extensive conformational dynamics at the site of the cross link, which extended over the entire DNA sequence. Since DNA duplexes containing the B-form and non-B-form ICL crosslinks have both been shown to be incised when incubated in mammalian whole cell extracts, while a matched normal duplex is not, we conclude that intrinsic DNA dynamics is not a requirement for specific damage incision of these ICLs. Instead, we propose a general model where

  15. Renal cell carcinoma arising in ipsilateral duplex system.

    PubMed

    Mohan, Harsh; Kundu, Reetu; Dalal, Usha

    2014-09-01

    Congenital anomalies of the kidney and urinary tract are common and include a wide anatomic spectrum. Duplex systems are one of the more common renal anomalies, with the majority being asymptomatic. Little is known about the molecular pathogenesis of these anomalies; however, certain causative genes have been implicated. The finding of renal cell carcinoma arising in a kidney with the duplication of pelvicalyceal system and ureters, as in the present case, is uncommon. The association between a duplex system and renal cell carcinoma may be more than a coincidence, requiring a deeper insight and further elucidation. PMID:26328175

  16. AMCC casting development, volume 2

    NASA Technical Reports Server (NTRS)

    1995-01-01

    PCC successfully cast and performed nondestructive testing, FPI and x-ray, on seventeen AMCC castings. Destructive testing, lab analysis and chemical milling, was performed on eleven of the castings and the remaining six castings were shipped to NASA or Aerojet. Two of the six castings shipped, lots 015 and 016, were fully processed per blueprint requirements. PCC has fully developed the gating and processing parameters of this part and feels the part could be implemented into production, after four more castings have been completed to ensure the repeatability of the process. The AMCC casting has been a technically challenging part due to its size, configuration, and alloy type. The height and weight of the wax pattern assembly necessitated the development of a hollow gating system to ensure structural integrity of the shell throughout the investment process. The complexity in the jacket area of the casting required the development of an innovative casting technology that PCC has termed 'TGC' or thermal gradient control. This method of setting up thermal gradients in the casting during solidification represents a significant process improvement for PCC and has been successfully implemented on other programs. The alloy, JBK75, is a relatively new alloy in the investment casting arena and required our engineering staff to learn the gating, processing, and dimensional characteristics of the material.

  17. Brazing titanium to stainless steel

    NASA Technical Reports Server (NTRS)

    Batista, R. I.

    1980-01-01

    Titanium and stainless-steel members are usually joined mechanically for lack of any other effective method. New approach using different brazing alloy and plating steel member with nickel resolves problem. Process must be carried out in inert atmosphere.

  18. Aspects of testing and selecting stainless steels for sea water applications

    SciTech Connect

    Steinsmo, U.; Rogne, T.; Drugli, J.M.

    1994-12-31

    In the period from 1980, highly alloyed stainless steels (i.e. Pitting Resistance Equivalent (PRE{sub N}) > 40) have been widely selected for chlorinated sea water systems in the Norwegian offshore industry. Recently failures have been reported -- severe crevice corrosion on flanges in a cooling water system and crevice corrosion at the threaded cast and forged joints in a fire water system. The failures highlights the question of corrosion testing and safe use limits for high alloyed stainless steels in sea water systems. This paper discusses three aspects regarding testing and selection of highly alloyed stainless steels for sea water application -- the relevancy of the electrochemical test methods used, the quality control system and the importance of repassivation.

  19. Melting and casting of FeAl-based cast alloy

    SciTech Connect

    Sikka, V.K.; Wilkening, D.; Liebetrau, J.; Mackey, B.

    1998-11-01

    The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{trademark} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast.

  20. Experimental Determination of Heat Transfer Within the Metal/Mold Gap in a DC Casting Mold: Part II. Effect of Casting Metal, Mold Material, and Other Casting Parameters

    NASA Astrophysics Data System (ADS)

    Prasad, Arvind; Bainbridge, Ian F.

    2013-07-01

    Extensive experimental studies were conducted to quantify the effect of different parameters that can affect the heat transfer from the metal to the mold during the steady-state phase of DC casting. In the first part previously published, the experimental technique was established and results were reported for the effect of gas type (atmosphere within the mold) and the gap between the metal and the mold. The results showed the significant effect of gas thermal conductivity and the metal-mold gap on the mold wall heat transfer coefficient. In this second publication on heat transfer in the mold wall region of a DC casting mold, the results from the effect of casting temperature, gas flow rate, casting alloy, mold material, and the mold insert material on the mold wall heat transfer coefficient are described. The experiments reported in the current paper show that these additional factors tested do not affect the heat flux through the mold wall to the same extent as the gap size or the gas type. The heat transfer coefficient changes by less than 5 pct when casting temperature is changed by ±25 K, less than 15 pct when the gas flow rate within the metal-mold gap flows at up to 3 LPM, and approximately 30 pct when the mold material is changed from stainless steel to AA601 to copper. Similar results were obtained when different insert materials were used. These results are explained with the help of an electrical analogy of heat transfer and are consistent with the heat transfer theory.

  1. A new view of the ultrasonic behavior of cast austenitic steels

    SciTech Connect

    Beller, L.S.

    1986-01-01

    A three-dimensionally anisotropic model of the cast austenitics is proposed and tested experimentally. The model predicts unique propagation modes and directions, which are observed experimentally in centrifugally cast stainless steel (CCSS) specimens, but which are not predicted by the single- preferred-axis model. It accounts for a large share of the difficulties noted in ultrasonic inspection of these materials by conventional techniques. The model also suggests a technique for significant improvement in signal/noise ratio (SNR) and in apparent attenuation; this technique is demonstrated experimentally to give striking improvements in SNR. In addition, a number of previously anomalous behaviors are explained by this model. 10 refs., 6 figs.

  2. Highly porous, low elastic modulus 316L stainless steel scaffold prepared by selective laser melting.

    PubMed

    Čapek, Jaroslav; Machová, Markéta; Fousová, Michaela; Kubásek, Jiří; Vojtěch, Dalibor; Fojt, Jaroslav; Jablonská, Eva; Lipov, Jan; Ruml, Tomáš

    2016-12-01

    Recently, porous metallic materials have been extensively studied as candidates for use in the fabrication of scaffolds and augmentations to repair trabecular bone defects, e.g. in surroundings of joint replacements. Fabricating these complex structures by using common approaches (e.g., casting and machining) is very challenging. Therefore, rapid prototyping techniques, such as selective laser melting (SLM), have been investigated for these applications. In this study, we characterized a highly porous (87 vol.%) 316L stainless steel scaffold prepared by SLM. 316L steel was chosen because it presents a biomaterial still widely used for fabrication of joint replacements and, from the practical point of view, use of the same material for fabrication of an augmentation and a joint replacement is beneficial for corrosion prevention. The results are compared to the reported properties of two representative nonporous 316L stainless steels prepared either by SLM or casting and subsequent hot forging. The microstructural and mechanical properties and the surface chemical composition and interaction with the cells were investigated. The studied material exhibited mechanical properties that were similar to those of trabecular bone (compressive modulus of elasticity ~0.15GPa, compressive yield strength ~3MPa) and cytocompatibility after one day that was similar to that of wrought 316L stainless steel, which is a commonly used biomaterial. Based on the obtained results, SLM is a suitable method for the fabrication of porous 316L stainless steel scaffolds with highly porous structures.

  3. Highly porous, low elastic modulus 316L stainless steel scaffold prepared by selective laser melting.

    PubMed

    Čapek, Jaroslav; Machová, Markéta; Fousová, Michaela; Kubásek, Jiří; Vojtěch, Dalibor; Fojt, Jaroslav; Jablonská, Eva; Lipov, Jan; Ruml, Tomáš

    2016-12-01

    Recently, porous metallic materials have been extensively studied as candidates for use in the fabrication of scaffolds and augmentations to repair trabecular bone defects, e.g. in surroundings of joint replacements. Fabricating these complex structures by using common approaches (e.g., casting and machining) is very challenging. Therefore, rapid prototyping techniques, such as selective laser melting (SLM), have been investigated for these applications. In this study, we characterized a highly porous (87 vol.%) 316L stainless steel scaffold prepared by SLM. 316L steel was chosen because it presents a biomaterial still widely used for fabrication of joint replacements and, from the practical point of view, use of the same material for fabrication of an augmentation and a joint replacement is beneficial for corrosion prevention. The results are compared to the reported properties of two representative nonporous 316L stainless steels prepared either by SLM or casting and subsequent hot forging. The microstructural and mechanical properties and the surface chemical composition and interaction with the cells were investigated. The studied material exhibited mechanical properties that were similar to those of trabecular bone (compressive modulus of elasticity ~0.15GPa, compressive yield strength ~3MPa) and cytocompatibility after one day that was similar to that of wrought 316L stainless steel, which is a commonly used biomaterial. Based on the obtained results, SLM is a suitable method for the fabrication of porous 316L stainless steel scaffolds with highly porous structures. PMID:27612756

  4. Volume MLS ray casting.

    PubMed

    Ledergerber, Christian; Guennebaud, Gaël; Meyer, Miriah; Bächer, Moritz; Pfister, Hanspeter

    2008-01-01

    The method of Moving Least Squares (MLS) is a popular framework for reconstructing continuous functions from scattered data due to its rich mathematical properties and well-understood theoretical foundations. This paper applies MLS to volume rendering, providing a unified mathematical framework for ray casting of scalar data stored over regular as well as irregular grids. We use the MLS reconstruction to render smooth isosurfaces and to compute accurate derivatives for high-quality shading effects. We also present a novel, adaptive preintegration scheme to improve the efficiency of the ray casting algorithm by reducing the overall number of function evaluations, and an efficient implementation of our framework exploiting modern graphics hardware. The resulting system enables high-quality volume integration and shaded isosurface rendering for regular and irregular volume data.

  5. Extrusion cast explosive

    DOEpatents

    Scribner, K.J.

    1985-11-26

    Disclosed is an improved, multiphase, high performance, high energy, extrusion cast explosive compositions, comprising, a crystalline explosive material; an energetic liquid plasticizer; a urethane prepolymer, comprising a blend of polyvinyl formal, and polycaprolactone; a polyfunctional isocyanate; and a catalyst. These new explosive compositions exhibit higher explosive content, a smooth detonation front, excellent stability over long periods of storage, and lower sensitivity to mechanical stimulants. 1 fig.

  6. Extrusion cast explosive

    DOEpatents

    Scribner, K.J.

    1985-01-29

    Improved, multiphase, high performance, high energy, extrusion cast explosive compositions, comprising, a crystalline explosive material; an energetic liquid plasticizer; a urethane prepolymer, comprising a blend of polyvinyl formal, and polycaprolactone; a polyfunctional isocyanate; and a catalyst are disclosed. These new explosive compositions exhibit higher explosive content, a smooth detonation front, excellent stability over long periods of storage, and lower sensitivity to mechanical stimulants. 1 fig.

  7. USGS ShakeCast

    USGS Publications Warehouse

    Wald, David; Lin, Kuo-Wan

    2007-01-01

    Automating, Simplifying, and Improving the Use of ShakeMap for Post-Earthquake Decisionmaking and Response. ShakeCast is a freely available, post-earthquake situational awareness application that automatically retrieves earthquake shaking data from ShakeMap, compares intensity measures against users facilities, and generates potential damage assessment notifications, facility damage maps, and other Web-based products for emergency managers and responders.

  8. NanoComposite Stainless Steel Powder Technologies

    SciTech Connect

    DeHoff, R.; Glasgow, C.

    2012-07-25

    Oak Ridge National Laboratory has been investigating a new class of Fe-based amorphous material stemming from a DARPA, Defense Advanced Research Projects Agency initiative in structural amorphous metals. Further engineering of the original SAM materials such as chemistry modifications and manufacturing processes, has led to the development of a class of Fe based amorphous materials that upon processing, devitrify into a nearly homogeneous distribution of nano sized complex metal carbides and borides. The powder material is produced through the gas atomization process and subsequently utilized by several methods; laser fusing as a coating to existing components or bulk consolidated into new components through various powder metallurgy techniques (vacuum hot pressing, Dynaforge, and hot isostatic pressing). The unique fine scale distribution of microstructural features yields a material with high hardness and wear resistance compared to material produced through conventional processing techniques such as casting while maintaining adequate fracture toughness. Several compositions have been examined including those specifically designed for high hardness and wear resistance and a composition specifically tailored to devitrify into an austenitic matrix (similar to a stainless steel) which poses improved corrosion behavior.

  9. A Standard Duplex Fiber Optic Receptacle/Connector: Requirements And Test Methods

    NASA Astrophysics Data System (ADS)

    Barrett, Mike; Khalil, Ragai

    1988-12-01

    The concept for using a duplex connector for the Fiber Distributed Data Interface (FDDI) was formalized in late 1983. The duplex requirements were driven by both the token ring topology and by the need to simplify connectivity between stations. Though most users speak in terms of a duplex connector or Medium Interface Connector (MIC), the FDDI Physical Medium Dependent (PMD) document only defines the physical parameters for a duplex receptacle. The receptacle is the boundary between the station and the cable plant of an FDDI network and hence the only location at which station conformance can be verified. The duplex connector or plug is therefore part of the FDDI cable plant.

  10. Computer Maintenance Operations Center (CMOC), showing duplexed cyber 170174 computers ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Computer Maintenance Operations Center (CMOC), showing duplexed cyber 170-174 computers - Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, Techinical Equipment Building, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA

  11. FRONT VIEW OF FACILITY 561, WHICH WAS ORIGINALLY A DUPLEX. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    FRONT VIEW OF FACILITY 561, WHICH WAS ORIGINALLY A DUPLEX. PHOTO SHOWS THE ONLY UNIT REMAINING, UNIT B (UNIT A WAS DEMOLISHED AFTER A FIRE). VIEW FACING NORTH - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Intersection of Acacia Road and Brich Circle, Pearl City, Honolulu County, HI

  12. Casting larger polycrystalline silicon ingots

    SciTech Connect

    Wohlgemuth, J.; Tomlinson, T.; Cliber, J.; Shea, S.; Narayanan, M.

    1995-08-01

    Solarex has developed and patented a directional solidification casting process specifically designed for photovoltaics. In this process, silicon feedstock is melted in a ceramic crucible and solidified into a large grained semicrystalline silicon ingot. In-house manufacture of low cost, high purity ceramics is a key to the low cost fabrication of Solarex polycrystalline wafers. The casting process is performed in Solarex designed casting stations. The casting operation is computer controlled. There are no moving parts (except for the loading and unloading) so the growth process proceeds with virtually no operator intervention Today Solarex casting stations are used to produce ingots from which 4 bricks, each 11.4 cm by 11.4 cm in cross section, are cut. The stations themselves are physically capable of holding larger ingots, that would yield either: 4 bricks, 15 cm by 15 an; or 9 bricks, 11.4 cm by 11.4 an in cross-section. One of the tasks in the Solarex Cast Polycrystalline Silicon PVMaT Program is to design and modify one of the castings stations to cast these larger ingots. If successful, this effort will increase the production capacity of Solarex`s casting stations by 73% and reduce the labor content for casting by an equivalent percentage.

  13. A study of chromium carbide precipitation at interphase boundaries in stainless steel welds

    SciTech Connect

    Willis, C.F.

    1990-04-01

    Sensitization is a deleterious process which can occur in stainless steels. It is caused by grain boundary or phase boundary precipitation of chromium carbides and the resulting formation of a chromium depleted zone adjacent to these boundaries. The carbides in question actually have the composition (Cr,Fe){sub 23}C{sub 6} (usually written M{sub 23}C{sub 6}), and precipitate in the temperature range 450--900{degree}C. Since a minimum chromium content is required to maintain the passive film necessary for resistance to electrochemical attack, the result of chromium depletion is that the steel becomes sensitized'' to possible intergranular corrosion. Sensitization often occurs as a result of welding operations. The material close to the fusion line reaches temperatures within the sensitization range. This region is called the heat affected zone (HAZ). Since many welds are multi-pass welds, the actual weld bead of one pass may lie in the heat affected zone of the next pass. The weld bead of the first pass might therefore be sensitized. Furthermore there are applications where welds will be exposed to sensitizing temperatures for very long periods of time, such as welded labels on retrievable nuclear waste containers. For these reasons the sensitization behavior of the actual weld-bead microstructures must be understood. It has been known for many years that duplex stainless steels (steels with both ferrite and austenite phases present at room temperature) have superior resistance to intergranular corrosion. A model has been proposed to explain the sensitization behavior of these alloys. This work will be concerned with testing the validity of aspects of this model using transmission electron microscopy and further understanding of the sensitization process in duplex stainless steel welds. 52 refs., 23 figs.

  14. Renal pelvis urothelial carcinoma of the upper moiety in complete right renal duplex: a case report

    PubMed Central

    Zhang, Yiran; Yu, Quanfeng; Zhang, Zhihong; Liu, Ranlu; Xu, Yong

    2015-01-01

    Urothelial carcinoma (UC) originated from renal pelvis is the common tumor of the urinary system, however, neoplasia of the renal pelvis in duplex kidneys is extremely rare, especially in the complete renal and ureteral duplex cases. We present the first case of renal pelvis UC of the upper moiety in a complete right renal duplex. This male patient has bilateral complete renal and ureteral duplex. To the best of our knowledge, this is the first reported case of renal pelvis UC in a complete renal duplex system. After this experience we feel that the diagnosis of renal pelvis UC in duplex kidneys is not so easy, and once the diagnosis is determined, the whole renal duplex units and bladder cuff or ectopic orifice should be excised radically. PMID:26823906

  15. Ion mobility spectrometry reveals duplex DNA dissociation intermediates.

    PubMed

    Burmistrova, Anastasia; Gabelica, Valérie; Duwez, Anne-Sophie; De Pauw, Edwin

    2013-11-01

    Electrospray ionization (ESI) soft desolvation is widely used to investigate fragile species such as nucleic acids. Tandem mass spectrometry (MS/MS) gives access to the gas phase energetics of the intermolecular interactions in the absence of solvent, by following the dissociation of mass-selected ions. Ion mobility mass spectrometry (IMS) provides indications on the tridimensional oligonucleotide structure by attributing a collision cross section (CCS) to the studied ion. Electrosprayed duplexes longer than eight bases pairs retain their helical structure in a solvent-free environment. However, the question of conformational changes under activation in MS/MS studies remains open. The objective of this study is to probe binding energetics and characterize the unfolding steps occurring prior to oligonucleotide duplex dissociation. Comparing the evolution of CCS with collision energy and breakdown curves, we characterize dissociation pathways involved in CID-activated DNA duplex separation into single strands, and we demonstrate here the existence of stable dissociation intermediates. At fixed duplex length, dissociation pathways were found to depend on the percentage of GC base pairs and on their position in the duplex. Our results show that pure GC sequences undergo a gradual compaction until reaching the dissociation intermediate: A-helix. Mixed AT-GC sequences were found to present at least two conformers: a classic B-helix and an extended structure where the GC tract is a B-helix and the AT tract(s) fray. The dissociation in single strands takes place from both conformers when the AT base pairs are enclosed between two GC tracts or only from the extended conformer when the AT tract is situated at the end(s) of the sequence.

  16. Cisplatin-induced duplex dissociation of complementary and destabilized short GG-containing duplex RNAs.

    PubMed

    Polonyi, Christopher; Alshiekh, Alak; Sarsam, Lamya A; Clausén, Maria; Elmroth, Sofi K C

    2014-08-21

    The ability of the anticancer active drug cisplatin to exert biological activity through interference with nucleic acid function is well documented. Since kinetics play a key role in determining product distributions in these systems, methods for accurate documentation of reactivity serve the purpose to identify preferential metal binding sites. In the present study, the aim has been to further explore a recently communicated approach (C. Polonyi and S. K. C. Elmroth, J. Chem. Soc., Dalton Trans., 2013, 42, 14959-14962) utilizing UV/vis spectroscopy and metal induced duplex RNA melting for monitoring of kinetics. More specifically, the sensitivity of the UV/vis-methodology has been evaluated by investigation of how overall length and changes of base-pairing in the close vicinity of a centrally located GG-site affect the rate of cisplatin binding, using the intracellularly active mono-aquated form of cisplatin (cis-Pt(NH3)2Cl(OH2)(+), ()) as the platination reagent. For this purpose, the reactivity of five different 13- to 17 base-pair duplex RNAs was monitored at 38 °C. A common trend of a ca. 10-fold reduction in reactivity was found to accompany an increase of bulk sodium concentration from CNa+ = 122 mM to 1.0 M. Typical half-lives are exemplified by the interaction of with the fully complementary 15-mer RNA-1 with t1/2 = ca. 0.5 and 4.8 hours, at CNa+ = 122 mM and 1.0 M respectively, and C = 45 μM. Lowering of melting temperature (Tm) was found to promote reactivity regardless of whether the change involved a decrease or increase of the RNA length. For example, at CNa+ = 1.0 M, truncation of the fully complementary and GG-containing 15-mer RNA-1 (Tm = 68.9 °C) to the 13-mer RNA-1-1-S (Tm = 63.9 °C) resulted in an increase of k2,app from ca. 0.9 M(-1) s(-1) to 2.0 M(-1) s(-1). Further, the 17-mer RNA-1-4 (Tm = 42.0 °C) with a central U4 bulge exhibited the highest reactivity of the sequences studied with k2,app = 4.0 M(-1) s(-1). The study shows that the

  17. High density tape casting system

    NASA Technical Reports Server (NTRS)

    Collins, Earl R., Jr. (Inventor)

    1989-01-01

    A system is provided for casting thin sheets (or tapes) of particles bound together, that are used for oxygen membranes and other applications, which enables the particles to be cast at a high packing density in a tape of uniform thickness. A slurry contains the particles, a binder, and a solvent, and is cast against the inside walls of a rotating chamber. Prior to spraying the slurry against the chamber walls, a solvent is applied to a container. The solvent evaporates to saturate the chamber with solvent vapor. Only then is the slurry cast. As a result, the slurry remains fluid long enough to spread evenly over the casting surface formed by the chamber, and for the slurry particles to become densely packed. Only then is the chamber vented to remove solvent, so the slurry can dry. The major novel feature is applying solvent vapor to a rotating chamber before casting slurry against the chamber walls.

  18. LOST FOAM CASTING OF MAGNESIUM ALLOYS

    SciTech Connect

    Han, Qingyou; Dinwiddie, Ralph Barton; Sklad, Philip S; Currie, Kenneth; Abdelrahman, Mohamed; Vondra, Fred; Walford, Graham; Nolan, Dennis J

    2007-01-01

    The lost foam casting process has been successfully used for making aluminum and cast iron thin walled castings of complex geometries. Little work has been carried out on cast magnesium alloys using the lost foam process. The article describes the research activities at Oak Ridge National Laboratory and Tennessee Technological University on lost foam casting of magnesium alloys. The work was focused on castings of simple geometries such as plate castings and window castings. The plate castings were designed to investigate the mold filling characteristics of magnesium and aluminum alloys using an infrared camera. The pate castings were then characterized for porosity distribution. The window castings were made to test the castability of the alloys under lost foam conditions. Significant differences between lost foam aluminum casting and lost foam magnesium casting have been observed.

  19. Cast dielectric composite linear accelerator

    DOEpatents

    Sanders, David M.; Sampayan, Stephen; Slenes, Kirk; Stoller, H. M.

    2009-11-10

    A linear accelerator having cast dielectric composite layers integrally formed with conductor electrodes in a solventless fabrication process, with the cast dielectric composite preferably having a nanoparticle filler in an organic polymer such as a thermosetting resin. By incorporating this cast dielectric composite the dielectric constant of critical insulating layers of the transmission lines of the accelerator are increased while simultaneously maintaining high dielectric strengths for the accelerator.

  20. Replacing London's cast iron mains

    SciTech Connect

    Thorne, A. ); Mathews, P. )

    1992-07-01

    This paper discusses the cast iron gas distribution systems that exist in many cities and contains considerable amounts of pipe that vary in age from 20 to 150 years. In many ways, cast iron is an excellent material. It is inherently corrosion resistant, easy to install and cheap. However, it is also brittle and smaller diameter cast iron pipe has a relatively low beam strength. This can lead, under some circumstances, to failure without external warning, with typically a full-circumferential failure. In congested areas this can lead to serious consequences. As a result, cast iron replacement programs are a common feature in such urban gas distribution systems.

  1. Low Frequency Phased Array Techniques for Crack Detection in Cast Austenitic Piping Welds: A Feasibility Study

    SciTech Connect

    Anderson, Michael T.; Cumblidge, Stephen E.; Doctor, Steven R.

    2007-01-01

    Studies conducted at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington have focused on developing and evaluating the reliability of nondestructive testing (NDT) approaches for coarse-grained stainless steel reactor components. The objective of this work is to provide information to the United States Nuclear Regulatory Commission (NRC) on the utility, effectiveness and limitation of NDT techniques as related to inservice testing of primary system piping components in pressurized water reactors. We examined cast stainless steel pipe specimens containing thermal and mechanical fatigue cracks located close to the weld roots and having inner and outer diameter surface geometrical conditions that simulate several water reactor primary piping configurations. In addition, segments of vintage centrifugally cast piping were examined to characterize the inherent acoustic noise and scattering caused by grain structures and to determine the consistency of ultrasonic responses when propagating through differing microstructures. Advanced ultrasonic phased array techniques were applied from the outside surface of these specimens using automated scanning devices and water coupling. The phased array approach was implemented with a modified instrument operating at low frequencies, and composite volumetric images of the specimens were generated. Results from laboratory studies for assessing crack detection effectiveness in cast stainless steel as a function of frequency are discussed in this paper.

  2. Surface-protein interactions on different stainless steel grades: effects of protein adsorption, surface changes and metal release.

    PubMed

    Hedberg, Y; Wang, X; Hedberg, J; Lundin, M; Blomberg, E; Wallinder, I Odnevall

    2013-04-01

    Implantation using stainless steels (SS) is an example where an understanding of protein-induced metal release from SS is important when assessing potential toxicological risks. Here, the protein-induced metal release was investigated for austenitic (AISI 304, 310, and 316L), ferritic (AISI 430), and duplex (AISI 2205) grades in a phosphate buffered saline (PBS, pH 7.4) solution containing either bovine serum albumin (BSA) or lysozyme (LSZ). The results show that both BSA and LSZ induce a significant enrichment of chromium in the surface oxide of all stainless steel grades. Both proteins induced an enhanced extent of released iron, chromium, nickel and manganese, very significant in the case of BSA (up to 40-fold increase), whereas both proteins reduced the corrosion resistance of SS, with the reverse situation for iron metal (reduced corrosion rates and reduced metal release in the presence of proteins). A full monolayer coverage is necessary to induce the effects observed.

  3. Study on Pot Forming of Induction Heater Type Rice Cookers by Forging Cast Process

    NASA Astrophysics Data System (ADS)

    Ohnishi, Masayuki; Yamaguchi, Mitsugi; Ohashi, Osamu

    This paper describes a study result on pot fabrication by the forging cast process of stainless steel with aluminum. Rice cooked with the new bowl-shaped pot for the induction heater type rice cookers is better tasting than rice cooked with the conventional cylindrical one, due to the achievement of better heat conduction and convection. The conventional pot is made of the clad sheet, consisting of stainless steel and aluminum. However, it is rather difficult to form a bowl shape from the clad sheet, primarily due to the problem of a material spring back. The fabrication of a new type of a pot was made possible by means of the adoption of a forging cast process instead of the clad sheet. In this process, iron powder is inserted between stainless steel and aluminum in order to alleviate the large difference on the coefficient of expansion between each material. It was made clear that the application of two kinds of iron particle, namely 10 μm size powder on the stainless steel side and 44 μm on the aluminum side, enables the joints to become strong enough. The joint strength of the new pot by this fabrication process was confirmed by the tests of the shear strength and the fatigue tests together with the stress analysis.

  4. When Your Child Needs a Cast

    MedlinePlus

    ... hard bandage that's usually made of material like fiberglass or plaster. Casts keep bones in place while ... water. Plaster of Paris casts are heavier than fiberglass casts and don't hold up as well ...

  5. Prototype casting fabrication by stereolithography

    SciTech Connect

    Cromwell, W.E.

    1992-03-01

    The evolution of the new technology of producing CAD models by ultraviolet solidification of resin materials (``STEREOLITHOGRAPHY``) continues to progress. The potential application area of rigid fabrication of prototype investment castings is becoming more feasible as we continue to successfully yield experimental castings by the ``SHELL`` processing method. This supplemental (to 11/90 publication) report briefly reviews the original project objectives, activities related to these objectives since November 1990, and progress made through December 1991. We discuss several new case studies involving new resin materials (and other materials) tested along with investment casting processing results. The most recent success, the processing of the highly complex ``C`` HOUSING design by the ``shell`` mold process in both aluminum and steel, will be discussed. This is considered a major breakthrough toward establishing this new technology as a viable approach to the rapid development of prototype investment castings, employing the most common aerospace (precision) cast process. Our future planning calls for expanding the study to help the investment casting industry in refining related processing techniques and to continue our evaluation of new resins suitable for the casting process. Present project planning calls for the completion of this study by the third quarter FY93 or sooner. We believe that with the continued excellent cooperation of our casting supplier study team and an accelerated effort by resin materials producers to further refine related materials, we can achieve all objectives during the planned time frame.

  6. Prototype casting fabrication by stereolithography

    SciTech Connect

    Cromwell, W.E.

    1992-03-01

    The evolution of the new technology of producing CAD models by ultraviolet solidification of resin materials ( STEREOLITHOGRAPHY'') continues to progress. The potential application area of rigid fabrication of prototype investment castings is becoming more feasible as we continue to successfully yield experimental castings by the SHELL'' processing method. This supplemental (to 11/90 publication) report briefly reviews the original project objectives, activities related to these objectives since November 1990, and progress made through December 1991. We discuss several new case studies involving new resin materials (and other materials) tested along with investment casting processing results. The most recent success, the processing of the highly complex C'' HOUSING design by the shell'' mold process in both aluminum and steel, will be discussed. This is considered a major breakthrough toward establishing this new technology as a viable approach to the rapid development of prototype investment castings, employing the most common aerospace (precision) cast process. Our future planning calls for expanding the study to help the investment casting industry in refining related processing techniques and to continue our evaluation of new resins suitable for the casting process. Present project planning calls for the completion of this study by the third quarter FY93 or sooner. We believe that with the continued excellent cooperation of our casting supplier study team and an accelerated effort by resin materials producers to further refine related materials, we can achieve all objectives during the planned time frame.

  7. Lost-Soap Aluminum Casting.

    ERIC Educational Resources Information Center

    Mihalow, Paula

    1980-01-01

    Lost-wax casting in sterling silver is a costly experience for the average high school student. However, this jewelry process can be learned at no cost if scrap aluminum is used instead of silver, and soap bars are used instead of wax. This lost-soap aluminum casting process is described. (Author/KC)

  8. Education and Caste in India

    ERIC Educational Resources Information Center

    Chauhan, Chandra Pal Singh

    2008-01-01

    This paper analyses the policy of reservation for lower castes in India. This policy is similar to that of affirmative action in the United States. The paper provides a brief overview of the caste system and discusses the types of groups that are eligible for reservation, based on data from government reports. The stance of this paper is that…

  9. Laser Safety Method For Duplex Open Loop Parallel Optical Link

    DOEpatents

    Baumgartner, Steven John; Hedin, Daniel Scott; Paschal, Matthew James

    2003-12-02

    A method and apparatus are provided to ensure that laser optical power does not exceed a "safe" level in an open loop parallel optical link in the event that a fiber optic ribbon cable is broken or otherwise severed. A duplex parallel optical link includes a transmitter and receiver pair and a fiber optic ribbon that includes a designated number of channels that cannot be split. The duplex transceiver includes a corresponding transmitter and receiver that are physically attached to each other and cannot be detached therefrom, so as to ensure safe, laser optical power in the event that the fiber optic ribbon cable is broken or severed. Safe optical power is ensured by redundant current and voltage safety checks.

  10. Hangingwall strain: A function of duplex shape and footwall topography

    NASA Astrophysics Data System (ADS)

    Butler, Robert W. H.

    1982-10-01

    The concept of piggy-back thrust tectonics implies that foreland is progressively accreted onto a developing thrust sheet during duplex formation. Lateral shape changes in duplexes in the hangingwall of a thrust and corrugations in the footwall will fold higher thrust sheets to give culminations and depressions. Balancing of parts of high level thrust sheets with lower sheets and foreland requires a sequence of extensional and compressional strains orientated normal to the thrust transport direction. Culmination walls will be sites of strike-parallel extension. Subsequent adjacent culminations will compress early culmination walls which will result in a sequence of irrotational strains. Examples of this geometry are given from the Moine Thrust zone of Northwest Scotland. The model allows a re-examination of strains and hangingwall evolution in some thrust sheets in the Helvetic and external zones of the Alps.

  11. Investigation of plastic deformation heterogeneities in duplex steel by EBSD

    SciTech Connect

    Wronski, S.; Tarasiuk, J.; Bacroix, B.; Baczmanski, A.; Braham, C.

    2012-11-15

    An EBSD analysis of a duplex steel (austeno-ferritic) deformed in tension up to fracture is presented. The main purpose of the paper is to describe, qualitatively and quantitatively, the differences in the behavior of the two phases during plastic deformation. In order to do so, several topological maps are measured on the deformed state using the electron backscatter diffraction technique. Distributions of grain size, misorientation, image quality factor and texture are then analyzed in detail. - Highlights: Black-Right-Pointing-Pointer Heterogeneities in duplex steel is studied. Black-Right-Pointing-Pointer The behavior of the two phases during plastic deformation is studied. Black-Right-Pointing-Pointer IQ factor distribution and misorientation characteristics are examined using EBSD.

  12. Investigation of hot cracking resistance of 2205 duplex steel

    NASA Astrophysics Data System (ADS)

    Adamiec, J.; Ścibisz, B.

    2010-02-01

    Austenitic duplex steel of the brand 2205 according to Avesta Sheffield is used for welded constructions (pipelines, tanks) in the petrol industry, chemical industry and food industry. It is important to know the range of high-temperature brittleness in designing welding technology for constructions made of this steel type. There is no data in literature concerning this issue. High-temperature brittleness tests using the simulator of heat flow device Gleeble 3800 were performed. The tests results allowed the evaluation of the characteristic temperatures in the brittleness temperature range during the joining of duplex steels, specifically the nil-strength temperature (NST) and nil-ductility temperatures (NDT) during heating, the strength and ductility recovery temperatures (DRT) during cooling, the Rfparameter (Rf = (Tliquidus - NDT)/NDT) describing the duplex steel inclination for hot cracking, and the brittleness temperature range (BTR). It has been stated that, for the examined steel, this range is wide and amounts to ca. 90 °C. The joining of duplex steels with the help of welding techniques creates a significant risk of hot cracks. After analysis of the DTA curves a liquidus temperature of TL = 1465 °C and a solidus temperature of TS = 1454 °C were observed. For NST a mean value was assumed, in which the cracks appeared for six samples; the temperature was 1381 °C. As the value of the NDT temperature 1367 °C was applied while for DRT the assumed temperature was 1375 °C. The microstructure of the fractures was observed using a Hitachi S-3400N scanning electron microscope (SEM). The analyses of the chemical composition were performed using an energy-dispersive X-ray spectrometer (EDS), Noran System Six of Thermo Fisher Scientific. Essential differences of fracture morphology type over the brittle temperature range were observed and described.

  13. View from east to west of family housing unit (duplex; ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View from east to west of family housing unit (duplex; either #27 or #87, as only the 7 is visible). Unit #27 was three-bedroom and located on 9th Street south. Unit #87 was a two-bedroom located on 4th Street north. These housing units have been removed - Stanley R. Mickelsen Safeguard Complex, Family Housing Units, In area bounded by Tenth Street North, Avenue A, & Avenue J, Nekoma, Cavalier County, ND

  14. All-atom crystal simulations of DNA and RNA duplexes

    PubMed Central

    Liu, Chunmei; Janowski, Pawel A.; Case, David A.

    2014-01-01

    Background Molecular dynamics simulations can complement experimental measures of structure and dynamics of biomolecules. The quality of such simulations can be tested by comparisons to models refined against experimental crystallographic data. Methods We report simulations of a DNA and RNA duplex in their crystalline environment. The calculations mimic the conditions for PDB entries 1D23 [d(CGATCGATCG)2] and 1RNA [(UUAUAUAUAUAUAA)2], and contain 8 unit cells, each with 4 copies of the Watson-Crick duplex; this yields in aggregate 64 µs of duplex sampling for DNA and 16 µs for RNA. Results The duplex structures conform much more closely to the average structure seen in the crystal than do structures extracted from a solution simulation with the same force field. Sequence-dependent variations in helical parameters, and in groove widths, are largely maintained in the crystal structure, but are smoothed out in solution. However, the integrity of the crystal lattice is slowly degraded in both simulations, with the result that the interfaces between chains become heterogeneous. This problem is more severe for the DNA crystal, which has fewer inter-chain hydrogen bond contacts than does the RNA crystal. Conclusions Crystal simulations using current force fields reproduce many features of observed crystal structures, but suffer from a gradual degradation of the integrity of the crystal lattice. General significance The results offer insights into force-field simulations that tests their ability to preserve weak interactions between chains, which will be of importance also in non-crystalline applications that involve binding and recognition. PMID:25255706

  15. Rapid commutation duplexer with phase-related outputs

    NASA Astrophysics Data System (ADS)

    Roveda, R.; Cattarin, G.; Digregorio, C.; Parrucci, U.

    Design criteria and the realization of an X-band waveguide rapid commutation duplexer, in production, are presented. By means of a digital TTL command it is capable of operating in three different conditions: all the power is conveyed to a single output; the poweer is equally divided between two in-phase outputs; and it is equally divided between two counter-phase outputs. In a monopulse radar this permits the electronic scanning of the antenna beam.

  16. Effect of 6-thioguanine on the stability of duplex DNA

    PubMed Central

    Bohon, Jen; de los Santos, Carlos R.

    2005-01-01

    The incorporation of 6-thioguanine (S6G) into DNA is a prerequisite for its cytotoxic action, but duplex structure is not significantly perturbed by the presence of the lesion [J. Bohon and C. R. de los Santos (2003) Nucleic Acids Res., 31, 1331–1338]. It is therefore possible that the mechanism of cytotoxicity relies on a loss of stability rather than a pathway involving direct structural recognition. The research described here focuses on the changes in thermodynamic properties of duplex DNA owing to the introduction of S6G as well as the kinetic properties of base pairs involving S6G. Replacement of a guanine in a G•C pair by S6G results in ∼1 kcal/mol less favorable Gibbs free energy of duplex formation at 37°C. S6G•T and G•T mismatch-containing duplexes have almost identical Gibbs free energy at 37°C, with values ∼3 kcal/mol less favorable than that of the control. Base pair stability is affected by S6G. The lifetime of the normal G•C base pair is ∼125 ms, whereas that of the G•T mismatch is below the detection limit. The lifetimes of S6G•C and S6G•T pairs are ∼7 and 2 ms, respectively, demonstrating that, although S6G significantly decreases the stability of the pairing with cytosine, it slightly increases that of a mismatch. PMID:15905476

  17. Fastcast: Integration and application of rapid prototyping and computational simulation to investment casting

    SciTech Connect

    Maguire, M.C.; Baldwin, M.D.; Atwood, C.L.

    1996-09-01

    The emergence of several rapid prototyping and manufacturing (RP and M) technologies is having a dramatic impact on investment casting. While the most successful of the rapid prototyping technologies are almost a decade old, relatively recent process advances in their application have produced some remarkable success in utilizing their products as patterns for investment castings. Sandia National Laboratories has been developed highly coupled experimental and computational capabilities to examine the investment casting process with the intention of reducing the amount of time required to manufacture castings, and to increase the quality of the finished product. This presentation will begin with process aspects of RP and M pattern production and handling, shell fabrication, burnout, and casting. The emphasis will be on how the use of Stereolithography (SL) or Selective Laser Sintered (SLS) patterns differs from more traditional wax pattern processes. Aspects of computational simulation to couple design, thermal analysis, and mold filling will be discussed. Integration of these topics is probably the greatest challenge to the use of concurrent engineering principles with investment casting. Sandia has conducted several experiments aimed at calibrating computer codes and providing data for input into these simulations. Studies involving materials as diverse as stainless steel and gold have been conducted to determine liquid metal behavior in molds via real time radiography. The application of these experiments to predictive simulations will be described.

  18. Duplex-Selective Ruthenium-based DNA Intercalators

    PubMed Central

    Shade, Chad M.; Kennedy, Robert D.; Rouge, Jessica L.; Rosen, Mari S.; Wang, Mary X.; Seo, Soyoung E.; Clingerman, Daniel J.

    2016-01-01

    We report the design and synthesis of small molecules that exhibit enhanced luminescence in the presence of duplex rather than single-stranded DNA. The local environment presented by a well-known [Ru(dipyrido[2,3-a:3',2'-c]phenazine)L2]2+-based DNA intercalator was modified by functionalizing the bipyridine ligands with esters and carboxylic acids. By systematically varying the number and charge of the pendant groups, it was determined that decreasing the electrostatic interaction between the intercalator and the anionic DNA backbone reduced single-strand interactions and translated to better duplex specificity. In studying this class of complexes, a single RuII complex emerged that selectively luminesces in the presence of duplex DNA with little to no background from interacting with single stranded DNA. This complex shows promise as a new dye capable of selectively staining double versus single-stranded DNA in gel electrophoresis, which cannot be done with conventional SYBR dyes. PMID:26119581

  19. Antisense properties of duplex- and triplex-forming PNAs.

    PubMed Central

    Knudsen, H; Nielsen, P E

    1996-01-01

    The potential of peptide nucleic acids (PNAs) as specific inhibitors of translation has been studied. PNAs with a mixed purine/pyrimidine sequence form duplexes, while homopyrimidine PNAs form (PNA)2/RNA triplexes with complementary sequences on RNA. We show here that neither of these PNA/RNA structures are substrates for RNase H. Translation experiments in cell-free extracts showed that a 15mer duplex-forming PNA blocked translation in a dose-dependent manner when the target was 5'-proximal to the AUG start codon on the RNA, whereas similar 10-, 15- or 20mer PNAs had no effect when targeted towards sequences in the coding region. Triplex-forming 10mer PNAs were efficient and specific antisense agents with a target overlapping the AUG start codon and caused arrest of ribosome elongation with a target positioned in the coding region of the mRNA. Furthermore, translation could be blocked with a 6mer bisPNA or with a clamp PNA, forming partly a triplex, partly a duplex, with its target sequence in the coding region of the mRNA. PMID:8602363

  20. Transpressive duplex and flower structure: Dent Fault System, NW England

    NASA Astrophysics Data System (ADS)

    Woodcock, Nigel H.; Rickards, Barrie

    2003-12-01

    Revised mapping along the Dent Fault (northwest England) has improved the resolution of folds and faults formed during Variscan (late Carboniferous) sinistral transpression. A NNE-trending east-down monocline, comprising the Fell End Syncline and Taythes Anticline, was forced in Carboniferous cover above a reactivated precursor to the Dent Fault within the Lower Palaeozoic basement. The Taythes Anticline is periclinal due to interference with earlier Acadian folds. The steep limb of the monocline was eventually cut by the west-dipping Dent Fault. The hangingwall of the Dent Fault was dissected by sub-vertical or east dipping faults, together forming a positive flower structure in cross-section and a contractional duplex in plan view. The footwall to the Dent Fault preserves evidence of mostly dip-slip displacements, whereas strike-slip was preferentially partitioned into the hangingwall faults. This pattern of displacement partitioning may be typical of transpressive structures in general. The faults of the Taythes duplex formed in a restraining overlap zone between the Dent Fault and the Rawthey Fault to the west. The orientations of the duplex faults were a response to kinematic boundary conditions rather than to the regional stress field directly. Kinematic constraints provided by the Dent and neighbouring Variscan faults yield a NNW-SSE regional shortening direction in this part of the Variscan foreland.

  1. Preformed posterior stainless steel crowns: an update.

    PubMed

    Croll, T P

    1999-02-01

    For almost 50 years, dentists have used stainless steel crowns for primary and permanent posterior teeth. No other type of restoration offers the convenience, low cost, durability, and reliability of such crowns when interim full-coronal coverage is required. Preformed stainless steel crowns have improved over the years. Better luting cements have been developed and different methods of crown manipulation have evolved. This article reviews stainless steel crown procedures for primary and permanent posterior teeth. Step-by-step placement of a primary molar stainless steel crown is documented and permanent molar stainless steel crown restoration is described. A method for repairing a worn-through crown also is reviewed.

  2. The fabrication of Stainless Stell Parts for MEMS

    SciTech Connect

    Terry J. Garino

    2002-01-01

    A micro-molding process was used to fabricate parts in the 0.1 to 10 mm size range from a stainless steel nano-powder. The two types of molds used were both produced from parts fabricated using the LIGA process so that they had precise dimensional tolerance and straight sidewalls. Rigid PMMA molds were made by injection molding and flexible silicone rubber molds were made by casting. Mold filling was accomplished by mixing the powder with epoxy to form a putty-like material that was then pressed into the mold cavities and allowed to cure. After pyrolysis of the epoxy, the parts were sintered in forming gas. The densification kinetics were measured in situ using a video system. Full densification was achieved after 1 hour at 1350 C. The microstructure of the sintered parts was examined using the SEM. The hardness, dimensional tolerance and surface roughness of the sintered parts were also measured.

  3. Deformable nature of various damaged DNA duplexes estimated by an electrochemical analysis on electrodes.

    PubMed

    Chiba, J; Aoki, S; Yamamoto, J; Iwai, S; Inouye, M

    2014-10-01

    We report bending flexibility of damaged duplexes possessing an apurinic/apyrimidinic (AP) site analogue, a cyclobutane pyrimidine dimer (CPD), and a pyrimidine(6-4)pyrimidone photoproduct (6-4PP). Based on the electrochemical evaluation on electrodes, the duplex flexibilities of the lesions increased in the following order: CPD < AP < 6-4PP. We discussed the possibility that the emerging local flexibility might be a good sign for UV-damaged DNA-binding proteins on duplexes.

  4. Casting process modeling using ProCAST and CAST2D

    SciTech Connect

    Shapiro, A.; Stein, W.; Raboin, P.

    1990-12-01

    Correctly modeling the fluid flow and heat transfer during the filling of a mold with a molten metal, and the thermal-mechanical physics of solidification and cooldown is important in predicting the quality of a cast part. Determining the dynamics of the flow and the free surface shape during filling are essential in establishing the temperature gradients in the melt and in the mold. Correctly modeling the physics of volume change on solidification, shrinkage on cooling, and contact resistance across the part-mold interface directly affects the cooling rate and ultimately the final cast shape and stress state of the cast part. In this paper we describe our current research efforts on modeling fluid fill using the commercial code ProCAST by UES, and thermal-mechanical solidification modeling using the code CAST2D by LLNL.

  5. Sixty Years of Casting Research

    NASA Astrophysics Data System (ADS)

    Campbell, John

    2015-11-01

    The 60 years of solidification research since the publication of Chalmer's constitutional undercooling in 1953 has been a dramatic advance of understanding which has and continues to be an inspiration. In contrast, 60 years of casting research has seen mixed fortunes. One of its success stories relates to improvements in inoculation of gray irons, and another to the discovery of spheroidal graphite iron, although both of these can be classified as metallurgical rather than casting advances. It is suggested that true casting advances have dated from the author's lab in 1992 when a critical surface turbulence condition was defined for the first time. These last 20 years have seen the surface entrainment issues of castings developed to a sufficient sophistication to revolutionize the performance of light alloy and steel foundries. However, there is still a long way to go, with large sections of the steel and Ni-base casting industries still in denial that casting defects are important or even exist. The result has been that special ingots are still cast poorly, and shaped casting operations have suffered massive losses. For secondary melted and cast materials, electro-slag remelting has the potential to be much superior to expensive vacuum arc remelting, which has cost our aerospace and defense industries dearly over the years. This failure to address and upgrade our processing of liquid metals is a serious concern, since the principle entrainment defect, the bifilm, is seen as the principle initiator of cracks in metals; in general, bifilms are the Griffith cracks that initiate failures by cracking. A new generation of crack resistant metals and engineering structures can now be envisaged.

  6. Cold Spray Repair of Martensitic Stainless Steel Components

    NASA Astrophysics Data System (ADS)

    Faccoli, M.; Cornacchia, G.; Maestrini, D.; Marconi, G. P.; Roberti, R.

    2014-12-01

    The possibility of using cold spray as repair technique of martensitic stainless steel components was evaluated through laboratory investigations. An austenitic stainless steel feedstock powder was chosen, instead of soft metals powders like nickel, copper, or aluminum, used for repairing components made in light alloy or cast iron. The present study directly compares the microstructure, the residual stresses, and the micro-hardness of repairs obtained by cold spray and by TIG welding, that is commonly used as repair technique in large steel components. XRD and optical metallographic analysis of the repairs showed that cold spray offers some advantages, inducing compressive residual stresses in the repair and avoiding alterations of the interface between repair and base material. For these reasons, a heat treatment after the cold spray repair is not required to restore the base material properties, whereas a post-weld heat treatment is needed after the welding repair. Cold spray repair also exhibits a higher micro-hardness than the welding repair. In addition, the cavitation erosion resistance of a cold spray coating was investigated through ultrasonic cavitation tests, and the samples worn surfaces were observed by scanning electron microscopy.

  7. Strip casting with fluxing agent applied to casting roll

    DOEpatents

    Williams, Robert S.; O'Malley, Ronald J.; Sussman, Richard C.

    1997-01-01

    A strip caster (10) for producing a continuous strip (24) includes a tundish (12) for containing a melt (14), a pair of horizontally disposed water cooled casting rolls (22) and devices (29) for electrostatically coating the outer peripheral chill surfaces (44) of the casting rolls with a powder flux material (56). The casting rolls are juxtaposed relative to one another for forming a pouting basin (18) for receiving the melt through a teeming tube (16) thereby establishing a meniscus (20) between the rolls for forming the strip. The melt is protected from the outside air by a non-oxidizing gas passed through a supply line (28) to a sealing chamber (26). A preferred flux is boron oxide having a melting point of about 550.degree. C. The flux coating enhances wetting of the steel melt to the casting roll and dissolves any metal oxide formed on the roll.

  8. Strip casting with fluxing agent applied to casting roll

    DOEpatents

    Williams, R.S.; O`Malley, R.J.; Sussman, R.C.

    1997-07-29

    A strip caster for producing a continuous strip includes a tundish for containing a melt, a pair of horizontally disposed water cooled casting rolls and devices for electrostatically coating the outer peripheral chill surfaces of the casting rolls with a powder flux material. The casting rolls are juxtaposed relative to one another for forming a pouting basin for receiving the melt through a teeming tube thereby establishing a meniscus between the rolls for forming the strip. The melt is protected from the outside air by a non-oxidizing gas passed through a supply line to a sealing chamber. A preferred flux is boron oxide having a melting point of about 550 C. The flux coating enhances wetting of the steel melt to the casting roll and dissolves any metal oxide formed on the roll. 3 figs.

  9. Strip casting apparatus and method

    DOEpatents

    Williams, R.S.; Baker, D.F.

    1988-09-20

    Strip casting apparatus including a molten-metal-holding container and a nozzle to deposit molten metal onto a moving chill drum to directly cast continuous metallic strip. The nozzle body includes a slot bounded between a back and a front lip. The slot width exceeds about 20 times the gap distance between the nozzle and the chill drum surface. Preferably, the slot width exceeds 0.5 inch. This method of strip casting minimizes pressure drop, insuring better metal-to-chill-drum contact which promotes heat transfer and results in a better quality metallic strip. 6 figs.

  10. Biomimetic Materials by Freeze Casting

    NASA Astrophysics Data System (ADS)

    Porter, Michael M.; Mckittrick, Joanna; Meyers, Marc A.

    2013-06-01

    Natural materials, such as bone and abalone nacre, exhibit exceptional mechanical properties, a product of their intricate microstructural organization. Freeze casting is a relatively simple, inexpensive, and adaptable materials processing method to form porous ceramic scaffolds with controllable microstructural features. After infiltration of a second polymeric phase, hybrid ceramic-polymer composites can be fabricated that closely resemble the architecture and mechanical performance of natural bone and nacre. Inspired by the narwhal tusk, magnetic fields applied during freeze casting can be used to further control architectural alignment, resulting in freeze-cast materials with enhanced mechanical properties.

  11. Pressure Rig for Repetitive Casting

    NASA Technical Reports Server (NTRS)

    Vasquez, P.; Hutto, W. R.

    1986-01-01

    Equipment life increased by improved insulation. New design cuts time of preparation for casting from several days to about 1 hour. Savings due to elimination of lengthy heating and drying operations associated with preparation of ceramic mold. Quality of casting improved because moisture in cavity eliminated by use of insulating material, and more uniform pressure applied to process. Commercial blanket insulator protects components from heat, increasing life of pressure rig and enabling repeated use. Improved heat protection allows casting of brass and other alloys with higher melting temperatures in pressure rig.

  12. Strip casting apparatus and method

    DOEpatents

    Williams, Robert S.; Baker, Donald F.

    1988-01-01

    Strip casting apparatus including a molten-metal-holding container and a nozzle to deposit molten metal onto a moving chill drum to directly cast continuous metallic strip. The nozzle body includes a slot bounded between a back and a front lip. The slot width exceeds about 20 times the gap distance between the nozzle and the chill drum surface. Preferably, the slot width exceeds 0.5 inch. This method of strip casting minimizes pressure drop, insuring better metal-to-chill-drum contact which promotes heat transfer and results in a better quality metallic strip.

  13. Constituent phases of the passive film formed on 2205 stainless steel by dynamic electrochemical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Cheng, Xue-Qun; Li, Cheng-Tao; Dong, Chao-Fang; Li, Xiao-Gang

    2011-02-01

    The passive film formed on 2205 duplex stainless steel (DSS) in 0.5 M NaHCO3+0.5 M NaCl aqueous solution was characterized by electrochemical measurements, including potentiodynamic anodic polarization and dynamic electrochemical impedance spectroscopy (DEIS). The results demonstrate that there is a great difference between the passive film evolutions of ferrite and austenite. The impedance values of ferrite are higher than those of austenite. The impedance peaks of ferritic and austenitic phases correspond to the potential of 0.15 and 0.25 V in the low potential range and correspond to 0.8 and 0.75 V in the high potential range. The evolutions of the capacitance of both phases are reverse compared to the evolutions of impedance. The thickness variations obtained from capacitance agree well with those of impedance analysis. The results can be used to explain why pitting corrosion occurs more easily in austenite phase than in ferrite phase.

  14. Oxidation Characteristics of Fe–18Cr–18Mn-Stainless Steel Alloys

    SciTech Connect

    Rawers, James

    2010-10-01

    Air oxidation studies of Fe-18Cr-18Mn stainless steels were conducted at 525°C, 625°C, and 725°C. Alloys were evaluated with respect to changes in oxidation properties as a result of interstitial additions of nitrogen and carbon and of minor solute additions of silicon, molybdenum, and nickel. Interstitial concentrations possibly had a small, positive effect on oxidation resistance. Minor solute additions significantly improved oxidation resistance but could also reduce interstitial solubility resulting in formation of chromium carbides. Loss of solute chromium resulted in a slight reduction in oxidation protection. Oxidation lasting over 500 hours produced a manganese rich, duplex oxide structure: an outer sesquioxide and an inner spinel oxide.

  15. Corrosivity of paper mill effluent and corrosion performance of stainless steel.

    PubMed

    Ram, Chhotu; Sharma, Chhaya; Singh, A K

    2015-01-01

    Present study relates to the corrosivity of paper mill effluent and corrosion performance of stainless steel (SS) as a construction material for the effluent treatment plant (ETP). Accordingly, immersion test and electrochemical polarization tests were performed on SS 304 L, 316 L and duplex 2205 in paper mill effluent and synthetic effluent. This paper presents electrochemical polarization measurements, performed for the first time to the best of the authors' information, to see the influence of chlorophenols on the corrosivity of effluents. The corrosivity of the effluent was observed to increase with the decrease in pH and increase in Cl- content while the addition of SO4- tends to inhibit corrosion. Mill effluent was found to be more corrosive as compared to synthetic effluent and has been attributed to the presence of various chlorophenols. Corrosion performance of SS was observed to govern by the presence of Cr, Mo and N contents. PMID:25188842

  16. Corrosivity of paper mill effluent and corrosion performance of stainless steel.

    PubMed

    Ram, Chhotu; Sharma, Chhaya; Singh, A K

    2015-01-01

    Present study relates to the corrosivity of paper mill effluent and corrosion performance of stainless steel (SS) as a construction material for the effluent treatment plant (ETP). Accordingly, immersion test and electrochemical polarization tests were performed on SS 304 L, 316 L and duplex 2205 in paper mill effluent and synthetic effluent. This paper presents electrochemical polarization measurements, performed for the first time to the best of the authors' information, to see the influence of chlorophenols on the corrosivity of effluents. The corrosivity of the effluent was observed to increase with the decrease in pH and increase in Cl- content while the addition of SO4- tends to inhibit corrosion. Mill effluent was found to be more corrosive as compared to synthetic effluent and has been attributed to the presence of various chlorophenols. Corrosion performance of SS was observed to govern by the presence of Cr, Mo and N contents.

  17. Using Low-Frequency Phased Arrays to Detect Cracks in Cast Austenitic Piping Components

    SciTech Connect

    Anderson, Michael T.; Cumblidge, Stephen E.; Doctor, Steven R.

    2005-12-30

    As part of a multi-year program funded by the United States Nuclear Regulatory Commission (US NRC) to address NDE reliability of inservice inspection (ISI) programs, recent studies conducted at the Pacific N¬orthwest National Laboratory (PNNL) in Richland, Washington, have focused on assessing novel NDE approaches for the inspection of coarse-grained, cast stainless steel reactor components. The primary objective of this work is to provide information to the US NRC on the utility, effec¬tiveness and reliability of ultrasonic testing (UT) and eddy current testing (ET) inspection techniques as related to the ISI of primary piping components in pressurized water reactors (PWRs). This paper describes progress, recent developments and early results from an assessment of a portion of this work relating to the ultrasonic low frequency phased array inspection technique. Westinghouse Owner’s Group (WOG) cast stainless steel pipe segments with thermal and mechanical fatigue cracks, PNNL samples containing thermal fatigue cracks and several blank vintage specimens having very coarse grains that are representative of early centrifugally cast piping installed in PWRs, are being used for assessing the inspection method. The phased array approach was implemented using an R/D Tech Tomoscan III system operating at 1.0 MHz and 500 kHz, providing composite volumetric images of the samples. Several dual, transmit-receive, custom designed low-frequency arrays are employed in laboratory trials. Results from laboratory studies for assessing detection of thermal and mechanical fatigue cracks in cast stainless steel piping welds are discussed. This work was sponsored by the U.S. Nuclear Regulatory Commission under Contract DE-AC06-76RLO 1830; NRC JCN Y6604; Mr. Wallace Norris, Program Monitor.

  18. 21 CFR 888.5940 - Cast component.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Cast component. 888.5940 Section 888.5940 Food and... ORTHOPEDIC DEVICES Surgical Devices § 888.5940 Cast component. (a) Identification. A cast component is a device intended for medical purposes to protect or support a cast. This generic type of device...

  19. 21 CFR 880.6185 - Cast cover.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Cast cover. 880.6185 Section 880.6185 Food and....6185 Cast cover. (a) Identification. A cast cover is a device intended for medical purposes that is made of waterproof material and placed over a cast to protect it from getting wet during a shower or...

  20. 21 CFR 880.6185 - Cast cover.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Cast cover. 880.6185 Section 880.6185 Food and....6185 Cast cover. (a) Identification. A cast cover is a device intended for medical purposes that is made of waterproof material and placed over a cast to protect it from getting wet during a shower or...

  1. 21 CFR 880.6185 - Cast cover.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Cast cover. 880.6185 Section 880.6185 Food and....6185 Cast cover. (a) Identification. A cast cover is a device intended for medical purposes that is made of waterproof material and placed over a cast to protect it from getting wet during a shower or...

  2. 21 CFR 888.5940 - Cast component.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Cast component. 888.5940 Section 888.5940 Food and... ORTHOPEDIC DEVICES Surgical Devices § 888.5940 Cast component. (a) Identification. A cast component is a device intended for medical purposes to protect or support a cast. This generic type of device...

  3. 21 CFR 888.5940 - Cast component.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Cast component. 888.5940 Section 888.5940 Food and... ORTHOPEDIC DEVICES Surgical Devices § 888.5940 Cast component. (a) Identification. A cast component is a device intended for medical purposes to protect or support a cast. This generic type of device...

  4. Force-Induced Rupture of a DNA Duplex: From Fundamentals to Force Sensors.

    PubMed

    Mosayebi, Majid; Louis, Ard A; Doye, Jonathan P K; Ouldridge, Thomas E

    2015-12-22

    The rupture of double-stranded DNA under stress is a key process in biophysics and nanotechnology. In this article, we consider the shear-induced rupture of short DNA duplexes, a system that has been given new importance by recently designed force sensors and nanotechnological devices. We argue that rupture must be understood as an activated process, where the duplex state is metastable and the strands will separate in a finite time that depends on the duplex length and the force applied. Thus, the critical shearing force required to rupture a duplex depends strongly on the time scale of observation. We use simple models of DNA to show that this approach naturally captures the observed dependence of the force required to rupture a duplex within a given time on duplex length. In particular, this critical force is zero for the shortest duplexes, before rising sharply and then plateauing in the long length limit. The prevailing approach, based on identifying when the presence of each additional base pair within the duplex is thermodynamically unfavorable rather than allowing for metastability, does not predict a time-scale-dependent critical force and does not naturally incorporate a critical force of zero for the shortest duplexes. We demonstrate that our findings have important consequences for the behavior of a new force-sensing nanodevice, which operates in a mixed mode that interpolates between shearing and unzipping. At a fixed time scale and duplex length, the critical force exhibits a sigmoidal dependence on the fraction of the duplex that is subject to shearing.

  5. Investment casting design of experiment. Final report

    SciTech Connect

    Owens, R.

    1997-10-01

    Specific steps in the investment casting process were analyzed in a designed experiment. The casting`s sensitivity to changes in these process steps was experimentally determined Dimensional and radiographic inspection were used to judge the sensitivity of the casting. Thirty-six castings of different pedigrees were poured and measured. Some of the dimensional inspection was conducted during the processing. It was confirmed that wax fixturing, number of gates, gate location, pour and mold temperature, pour speed, and cooling profile all affected the radiographic quality of the casting. Gate and runner assembly techniques, number of gates, and mold temperature affect the dimensional quality of the casting.

  6. Strong and light plaster casts?

    PubMed

    Stewart, Todd; Cheong, Wen; Barr, Victoria; Tang, Daniel

    2009-08-01

    Three geometries of volar slab plaster cast for the stabilisation of wrist fractures were investigated. It was found that by moulding reinforcement ridges on the inferior surface of the slab the strength and stiffness could be doubled with only a 20% increase in weight. It was discovered that to provide the same increase in strength with a traditional cast the entire thickness of the cast would have to be doubled, with a 100% increase in weight that would be cumbersome to most users. Bending theory is presented in a simple manner to allow clinicians to understand how reinforcement mouldings can improve the strength and stiffness of plaster casts without adversely influencing weight, or cost.

  7. Casting Using A Polystyrene Pattern

    NASA Technical Reports Server (NTRS)

    Vasquez, Peter; Guenther, Bengamin; Vranas, Thomas; Veneris, Peter; Joyner, Michael

    1993-01-01

    New technique for making metal aircraft models saves significant amount of time and effort in comparison with conventional lost-wax method. Produces inexpensive, effective wind-tunnel models. Metal wind-tunnel model cast by use of polystyrene pattern.

  8. Nano-composite stainless steel

    DOEpatents

    Dehoff, Ryan R.; Blue, Craig A.; Peter, William H.; Chen, Wei; Aprigliano, Louis F.

    2015-07-14

    A composite stainless steel composition is composed essentially of, in terms of wt. % ranges: 25 to 28 Cr; 11 to 13 Ni; 7 to 8 W; 3.5 to 4 Mo; 3 to 3.5 B; 2 to 2.5 Mn; 1 to 1.5 Si; 0.3 to 1.7 C; up to 2 O; balance Fe. The composition has an austenitic matrix phase and a particulate, crystalline dispersed phase.

  9. Oscillator for continuous casting mold

    SciTech Connect

    Behrends, G.

    1993-06-15

    In a continuous casting machine comprising a chilled mold disposed to receive molten metal which is discharged from the mold as a curved casting having a predetermined casting radius, and an oscillating drive for oscillating the mold relative to the casting, wherein the improvement described comprises mold guidance means having a first tensile element having an inner end and an outer end, the outer end being anchored to a fixed external frame and the inner end being secured to move with the mold, the first tensile element lying on a first radius extending from the center of curvature of said pre-determined casting radius; and a second tensile element having an inner and an outer end both anchored to a fixed external frame and secured to move with the mold intermediate the inner and outer ends, at least one end having variable tensioning means adapted to apply a tensile force to the second tensile element, the second tensile element lying on a second radius extending from the center of curvature of said predetermined casting radius.

  10. Nickel: makes stainless steel strong

    USGS Publications Warehouse

    Boland, Maeve A.

    2012-01-01

    Nickel is a silvery-white metal that is used mainly to make stainless steel and other alloys stronger and better able to withstand extreme temperatures and corrosive environments. Nickel was first identified as a unique element in 1751 by Baron Axel Fredrik Cronstedt, a Swedish mineralogist and chemist. He originally called the element kupfernickel because it was found in rock that looked like copper (kupfer) ore and because miners thought that "bad spirits" (nickel) in the rock were making it difficult for them to extract copper from it. Approximately 80 percent of the primary (not recycled) nickel consumed in the United States in 2011 was used in alloys, such as stainless steel and superalloys. Because nickel increases an alloy's resistance to corrosion and its ability to withstand extreme temperatures, equipment and parts made of nickel-bearing alloys are often used in harsh environments, such as those in chemical plants, petroleum refineries, jet engines, power generation facilities, and offshore installations. Medical equipment, cookware, and cutlery are often made of stainless steel because it is easy to clean and sterilize. All U.S. circulating coins except the penny are made of alloys that contain nickel. Nickel alloys are increasingly being used in making rechargeable batteries for portable computers, power tools, and hybrid and electric vehicles. Nickel is also plated onto such items as bathroom fixtures to reduce corrosion and provide an attractive finish.

  11. Developmental techniques for ultrasonic flaw detection and characterization in stainless steel. [PWR

    SciTech Connect

    Kupperman, D.S.

    1983-04-01

    Flaw detection and characterization by ultrasonic methods is particularly difficult for stainless steel. This paper focuses on two specific problem areas: (a) the inspection of centrifugally cast stainless steel (CCSS) and (b) the differentiation of intergranular stress-corrosion cracking (IGSCC) from geometrical reflectors such as the weld root. To help identify optimal conditions for the ultrasonic inspection of CCSS, the effect of frequency on propagation of longitudinal and shear waves was examined in both isotropic and anisotropic samples. Good results were obtained with isotropic CCSS and 0.5-MHz angle beam shear waves. The use of beam-scattering patterns (i.e. signal amplitude vs skew angle) as a tool for discriminating IGSCC from geometrical reflectors is also discussed.

  12. High Density Die Casting (HDDC): new frontiers in the manufacturing of heat sinks

    NASA Astrophysics Data System (ADS)

    Sce, Andrea; Caporale, Lorenzo

    2014-07-01

    Finding a good solution for thermal management problems is every day more complex. due to the power density and the required performances. When a solution suitable for high volumes is needed. die-casting and extrusion are the most convenient technologies. However designers have to face the well-known limitations for those processes. High Density Die Casting (HDDC) is a process under advanced development. in order to overcome the extrusion and traditional die casting limits by working with alloys having much better thermal performances than the traditional die-casting process. while keeping the advantages of a flexible 3D design and a low cost for high volumes. HDDC offers the opportunity to design combining different materials (aluminium and copper. aluminium and stainless steel) obtaining a structure with zero porosity and overcoming some of die-casting limits. as shown in this paper. A dedicated process involving embedded heat pipes is currently under development in order to offer the possibility to dramatically improve the heat spreading.

  13. CC process optimization through an improved thermal modeling of the cast steel products

    SciTech Connect

    Selaries, J.; Hoffbeck, AM.; Jolivet, JM.; Niederlaender, M.; Perrin, G.; Bobadilla, M.

    1997-12-31

    Heat transfer models developed for continuous casting are more and more becoming simulation tools for defining, from metallurgical criteria, the values of casting parameters (superheat, primary and secondary cooling, casting speed,...) in order to obtain quality products (free from surface cracks and having a low level of central segregation) in the framework of a given production. From this outlook, it is important to have reliable models for the description of the basic mechanisms (heat transfer, microsegregation) as well as for the values relative to the thermophysical data to be used (thermal conductivity, density, enthalpy,...). The studies conducted by IRSID in these fields have made it possible to define the improvements to be brought to the thermal models of continuous casting that are already available. In the first part of this paper, the principles of the improvements brought to the basic models are presented in detail: mathematical formulation taking into account the evolution of the thermal conductivity and the density of steel with temperature, introduction of the microsegregation model adapted to various steel grades (low carbon steels, high carbon steels, stainless steels,...) and selection of the thermophysical data (thermal conductivity, density, enthalpy) with respect to the steel grade. In the second part, some industrial applications of the new model for heat transfers in continuous casting are presented.

  14. Effect of cold working and isothermal aging on the precipitation of sigma phase in 2205 duplex stainless steel

    SciTech Connect

    Cho, Hoon-Sung; Lee, Kwangmin

    2013-01-15

    A comprehensive understanding of the formation of the sigma phase resulting from the eutectoid reaction ({delta} {yields} {sigma} + {gamma}{sub 2}) is required. The kinetics necessary for the eutectoid reaction are closely related to the amount of plastic deformation in DSS. This work investigates the microstructural evolution of the {sigma} phase in a 22Cr-5Ni SAF 2205 DSS after subsequent plastic deformation and isothermal aging. The precipitation of the {sigma} phase resulted from the higher driving force for precipitating intermetallic compounds and the higher diffusion rate of their elements by cold-rolling, as well as the sufficient supply of molybdenum. The maximum amount of {sigma} phase precipitation remarkably increased with an increasing cold deformation, as compared with the non-cold-rolled materials. - Highlights: Black-Right-Pointing-Pointer The microstructural evolution of sigma phase has been characterized. Black-Right-Pointing-Pointer The chemical compositions of sigma phases were analyzed using TEM-EDX. Black-Right-Pointing-Pointer The effect of cold deformation on the precipitation of sigma phase was investigated.

  15. Titan Casts Revealing Shadow

    NASA Astrophysics Data System (ADS)

    2004-05-01

    A rare celestial event was captured by NASA's Chandra X-ray Observatory as Titan -- Saturn's largest moon and the only moon in the Solar System with a thick atmosphere -- crossed in front of the X-ray bright Crab Nebula. The X-ray shadow cast by Titan allowed astronomers to make the first X-ray measurement of the extent of its atmosphere. On January 5, 2003, Titan transited the Crab Nebula, the remnant of a supernova explosion that was observed to occur in the year 1054. Although Saturn and Titan pass within a few degrees of the Crab Nebula every 30 years, they rarely pass directly in front of it. "This may have been the first transit of the Crab Nebula by Titan since the birth of the Crab Nebula," said Koji Mori of Pennsylvania State University in University Park, and lead author on an Astrophysical Journal paper describing these results. "The next similar conjunction will take place in the year 2267, so this was truly a once in a lifetime event." Animation of Titan's Shadow on Crab Nebula Animation of Titan's Shadow on Crab Nebula Chandra's observation revealed that the diameter of the X-ray shadow cast by Titan was larger than the diameter of its solid surface. The difference in diameters gives a measurement of about 550 miles (880 kilometers) for the height of the X-ray absorbing region of Titan's atmosphere. The extent of the upper atmosphere is consistent with, or slightly (10-15%) larger, than that implied by Voyager I observations made at radio, infrared, and ultraviolet wavelengths in 1980. "Saturn was about 5% closer to the Sun in 2003, so increased solar heating of Titan may account for some of this atmospheric expansion," said Hiroshi Tsunemi of Osaka University in Japan, one of the coauthors on the paper. The X-ray brightness and extent of the Crab Nebula made it possible to study the tiny X-ray shadow cast by Titan during its transit. By using Chandra to precisely track Titan's position, astronomers were able to measure a shadow one arcsecond in

  16. Duplex development and abandonment during evolution of the Lewis thrust system, southern Glacier National Park, Montana

    NASA Astrophysics Data System (ADS)

    Yin, An; Kelty, Thomas K.; Davis, Gregory A.

    1989-09-01

    Geologic mapping in southern Glacier National Park, Montana, reveals the presence of two duplexes sharing the same floor thrust fault, the Lewis thrust. The westernmost duplex (Brave Dog Mountain) includes the low-angle Brave Dog roof fault and Elk Mountain imbricate system, and the easternmost (Rising Wolf Mountain) duplex includes the low-angle Rockwell roof fault and Mt. Henry imbricate system. The geometry of these duplexes suggests that they differ from previously described geometric-kinematic models for duplex development. Their low-angle roof faults were preexisting structures that were locally utilized as roof faults during the formation of the imbricate systems. Crosscutting of the Brave Dog fault by the Mt. Henry imbricate system indicates that the two duplexes formed at different times. The younger Rockwell-Mt. Henry duplex developed 20 km east of the older Brave Dog-Elk Mountain duplex; the roof fault of the former is at a higher structural level. Field relations confirm that the low-angle Rockwell fault existed across the southern Glacier Park area prior to localized formation of the Mt. Henry imbricate thrusts beneath it. These thrusts kinematically link the Rockwell and Lewis faults and may be analogous to P shears that form between two synchronously active faults bounding a simple shear system. The abandonment of one duplex and its replacement by another with a new and higher roof fault may have been caused by (1) warping of the older and lower Brave Dog roof fault during the formation of the imbricate system (Elk Mountain) beneath it, (2) an upward shifting of the highest level of a simple shear system in the Lewis plate to a new decollement level in subhorizontal belt strata (= the Rockwell fault) that lay above inclined strata within the first duplex, and (3) a reinitiation of P-shear development (= Mt. Henry imbricate faults) between the Lewis thrust and the subparallel, synkinematic Rockwell fault.

  17. Water-evaporation reduction by duplex films: application to the human tear film.

    PubMed

    Cerretani, Colin F; Ho, Nghia H; Radke, C J

    2013-09-01

    Water-evaporation reduction by duplex-oil films is especially important to understand the physiology of the human tear film. Secreted lipids, called meibum, form a duplex film that coats the aqueous tear film and purportedly reduces tear evaporation. Lipid-layer deficiency is correlated with the occurrence of dry-eye disease; however, in-vitro experiments fail to show water-evaporation reduction by tear-lipid duplex films. We review the available literature on water-evaporation reduction by duplex-oil films and outline the theoretical underpinnings of spreading and evaporation kinetics that govern behavior of these systems. A dissolution-diffusion model unifies the data reported in the literature and identifies dewetting of duplex films into lenses as a key challenge to obtaining significant evaporation reduction. We develop an improved apparatus for measuring evaporation reduction by duplex-oil films including simultaneous assessment of film coverage, stability, and temperature, all under controlled external mass transfer. New data reported in this study fit into the larger body of work conducted on water-evaporation reduction by duplex-oil films. Duplex-oil films of oxidized mineral oil/mucin (MOx/BSM), human meibum (HM), and bovine meibum (BM) reduce water evaporation by a dissolution-diffusion mechanism, as confirmed by agreement between measurement and theory. The water permeability of oxidized-mineral-oil duplex films agrees with those reported in the literature, after correction for the presence of mucin. We find that duplex-oil films of bovine and human meibum at physiologic temperature reduce water evaporation only 6-8% for a 100-nm film thickness pertinent to the human tear film. Comparison to in-vivo human tear-evaporation measurements is inconclusive because evaporation from a clean-water surface is not measured and because the mass-transfer resistance is not characterized.

  18. Energy Saving Melting and Revert Reduction Technology (Energy-SMARRT): Clean Steel Casting Production

    SciTech Connect

    Kuyucak, Selcuk; Li, Delin

    2013-12-31

    Inclusions in steel castings can cause rework, scrap, poor machining, and reduced casting performance, which can obviously result in excess energy consumption. Significant progress in understanding inclusion source, formation and control has been made. Inclusions can be defined as non-metallic materials such as refractory, sand, slag, or coatings, embedded in a metallic matrix. This research project has focused on the mold filling aspects to examine the effects of pouring methods and gating designs on the steel casting cleanliness through water modeling, computer modeling, and melting/casting experiments. Early in the research project, comprehensive studies of bottom-pouring water modeling and low-alloy steel casting experiments were completed. The extent of air entrainment in bottom-poured large castings was demonstrated by water modeling. Current gating systems are designed to prevent air aspiration. However, air entrainment is equally harmful and no prevention measures are in current practice. In this study, new basin designs included a basin dam, submerged nozzle, and nozzle extension. The entrained air and inclusions from the gating system were significantly reduced using the new basin method. Near the end of the project, there has been close collaboration with Wescast Industries Inc., a company manufacturing automotive exhaust components. Both computer modeling using Magma software and melting/casting experiments on thin wall turbo-housing stainless steel castings were completed in this short period of time. Six gating designs were created, including the current gating on the pattern, non-pressurized, partially pressurized, naturally pressurized, naturally pressurized without filter, and radial choke gating without filter, for Magma modeling. The melt filling velocity and temperature were determined from the modeling. Based on the simulation results, three gating designs were chosen for further melting and casting experiments on the same casting pattern using

  19. Low Frequency Phased Array Application for Crack Detection in Cast Austenitic Piping

    SciTech Connect

    Anderson, Michael T.; Cumblidge, Stephen E.; Doctor, Steven R.

    2006-10-01

    As part of a multi-year program funded by the United States Nuclear Regulatory Commission (US NRC) to address nondestructive examination (NDE) reliability of inservice inspection (ISI) programs, studies conducted at the Pacific N¬orthwest National Laboratory (PNNL) in Richland, Washington, have focused on assessing novel NDE approaches for the inspection of coarse-grained, cast stainless steel reactor components. The primary objective of this work is to provide information to the US NRC on the utility, effec¬tiveness and reliability of ultrasonic testing (UT) as related to the ISI of primary piping components in US commercial nuclear power plants. This paper describes progress, recent developments and results from an assessment of a portion of the work relating to the ultrasonic low frequency phased array inspection technique. Westinghouse Owner’s Group (WOG) cast stainless steel pipe segments with thermal and mechanical fatigue cracks, PNNL samples containing thermal fatigue cracks and several blank vintage specimens having very coarse grains that are representative of early centrifugally cast piping installed in PWRs, were used for assessing the inspection method. The phased array approach was implemented using an R/D Tech Tomoscan III system operating at 1.0 MHz and 500 kHz, providing composite volumetric images of the samples. Several dual, transmit-receive, custom designed low-frequency arrays were employed in laboratory trials. Results from laboratory studies for assessing detection, localization and length sizing effectiveness are discussed.

  20. Fillability of Thin-Wall Steel Castings

    SciTech Connect

    Robert C. Voigt; Joseph Bertoletti; Andrew Kaley; Sandi Ricotta; Travis Sunday

    2002-07-30

    The use of steel components is being challenged by lighter nonferrous or cast iron components. The development of techniques for enhancing and ensuring the filability of thin-wall mold cavities is most critical for thinner wall cast steel production. The purpose of this research was to develop thin-wall casting techniques that can be used to reliably produce thin-wall castings from traditional gravity poured sand casting processes. The focus of the research was to enhance the filling behavior to prevent misrunds. Experiments were conducted to investigate the influence of various foundry variables on the filling of thin section steel castings. These variables include casting design, heat transfer, gating design, and metal fluidity. Wall thickness and pouring temperature have the greatest effect on casting fill. As wall thickness increases the volume to surface area of the casting increases, which increases the solidification time, allowing the metal to flow further in thicker sect ions. Pouring time is another significant variable affecting casting fill. Increases or decreases of 20% in the pouring time were found to have a significant effect on the filling of thin-wall production castings. Gating variables, including venting, pouring head height, and mold tilting also significantly affected thin-wall casting fill. Filters offer less turbulent, steadier flow, which is appropriate for thicker castings, but they do not enhance thin-wall casting fill.

  1. Duplex Identification of Staphylococcus aureus by Aptamer and Gold Nanoparticles.

    PubMed

    Chang, Tianjun; Wang, Libo; Zhao, Kexu; Ge, Yu; He, Meng; Li, Gang

    2016-06-01

    Staphylococcus aureus is the top common pathogen causing infections and food poisoning. Identification of S. aureus is crucial for the disease diagnosis and regulation of food hygiene. Herein, we report an aptamer-AuNPs based method for duplex identification of S. aureus. Using AuNPs as an indicator, SA23, an aptamer against S. aureus, can well identify its target from Escherichia coli, Listeria monocytogenes and Pseudomonas aeruginosa. Furthermore, we find citrate-coated AuNPs can strongly bind to S. aureus, but not bind to Salmonella enterica and Proteus mirabilis, which leads to different color changes in salt solution. This colorimetric response is capable of distinguishing S. aureus from S. enteritidis and P. mirabilis. Thus, using the aptasensor and AuNPs together, S. aureus can be accurately identified from the common pathogens. This duplex identification system is a promising platform for simple visual identification of S. aureus. Additionally, in the aptasensing process, bacteria are incubated with aptamers and then be removed before the aptamers adding to AuNPs, which may avoid the interactions between bacteria and AuNPs. This strategy can be potentially applied in principle to detect other cells by AuNPs-based aptasensors.

  2. Cosmetic leg veins: evaluation using duplex venous imaging.

    PubMed

    Thibault, P; Bray, A; Wlodarczyk, J; Lewis, W

    1990-07-01

    The records of 305 consecutive patients who had presented with cosmetic symptoms related to varicose and/or spider veins over a 12-month period were studied. Following clinical assessment, 250 (82%) patients were referred for duplex venous imaging. A total of 500 lower limbs were evaluated; 236 (47%) were documented to have incompetence in the superficial venous system (long or short saphenous veins). Only 6 (1%) limbs had deep venous incompetence and 45 (9%) limbs were found to have perforator incompetence. Short saphenous vein incompetence was found in 59 (12%) limbs. In the long saphenous vein there was a consistent pattern of an increasing incidence of incompetence from the saphenofemoral junction down to the below-knee segment. The duplex imaging findings were applied to determine the optimal treatment, ie, whether surgery, sclerotherapy, or a combination of both would provide the best short- and long-term results. The possible etiology and pathophysiology of spider and varicose veins are discussed in relation to these results.

  3. Resonance energy transfer in DNA duplexes labeled with localized dyes.

    PubMed

    Cunningham, Paul D; Khachatrian, Ani; Buckhout-White, Susan; Deschamps, Jeffrey R; Goldman, Ellen R; Medintz, Igor L; Melinger, Joseph S

    2014-12-18

    The growing maturity of DNA-based architectures has raised considerable interest in applying them to create photoactive light harvesting and sensing devices. Toward optimizing efficiency in such structures, resonant energy transfer was systematically examined in a series of dye-labeled DNA duplexes where donor-acceptor separation was incrementally changed from 0 to 16 base pairs. Cyanine dyes were localized on the DNA using double phosphoramidite attachment chemistry. Steady state spectroscopy, single-pair fluorescence, time-resolved fluorescence, and ultrafast two-color pump-probe methods were utilized to examine the energy transfer processes. Energy transfer rates were found to be more sensitive to the distance between the Cy3 donor and Cy5 acceptor dye molecules than efficiency measurements. Picosecond energy transfer and near-unity efficiencies were observed for the closest separations. Comparison between our measurements and the predictions of Förster theory based on structural modeling of the dye-labeled DNA duplex suggest that the double phosphoramidite linkage leads to a distribution of intercalated and nonintercalated dye orientations. Deviations from the predictions of Förster theory point to a failure of the point dipole approximation for separations of less than 10 base pairs. Interactions between the dyes that alter their optical properties and violate the weak-coupling assumption of Förster theory were observed for separations of less than four base pairs, suggesting the removal of nucleobases causes DNA deformation and leads to enhanced dye-dye interaction. PMID:25397906

  4. Duplex carburetor and intake system for internal combustion engines

    SciTech Connect

    Yokoyama, H.; Ishida, T.

    1984-06-05

    A duplex carburetor for an internal combustion engine has a primary barrel having a primary venturi for supplying an air-fuel mixture to an intake manifold under a full range of engine loads and a secondary barrel having a secondary venturi for supplying an air-fuel mixture to the manifold under higher engine loads. The primary venturi has a cross section which ranges from 20% to 30% of that of the secondary venturi. The secondary barrel has a flattened cross-sectional shape such as of a segment of a circle of an ellipse, and is located adjacent to the primary barrel. The intake manifold is of a duplex construction having primary and secondary common passages connected to the primary and secondary barrels, respectively, of the carburetor. The secondary passage of the manifold has a flattened cross-sectional shape such as of a segment of a circle or an ellipse, and is positioned adjacent to the primary passage. The primary passage extends through a region where the secondary passage is divided into a plurality of secondary branches, and is located immediately in front of the shortest one of the secondary branch. The primary passage is also branched into a plurality of primary branches, the shortest of which is displaced out of axial alignment with a central axis of the intake manifold.

  5. Duplex Identification of Staphylococcus aureus by Aptamer and Gold Nanoparticles.

    PubMed

    Chang, Tianjun; Wang, Libo; Zhao, Kexu; Ge, Yu; He, Meng; Li, Gang

    2016-06-01

    Staphylococcus aureus is the top common pathogen causing infections and food poisoning. Identification of S. aureus is crucial for the disease diagnosis and regulation of food hygiene. Herein, we report an aptamer-AuNPs based method for duplex identification of S. aureus. Using AuNPs as an indicator, SA23, an aptamer against S. aureus, can well identify its target from Escherichia coli, Listeria monocytogenes and Pseudomonas aeruginosa. Furthermore, we find citrate-coated AuNPs can strongly bind to S. aureus, but not bind to Salmonella enterica and Proteus mirabilis, which leads to different color changes in salt solution. This colorimetric response is capable of distinguishing S. aureus from S. enteritidis and P. mirabilis. Thus, using the aptasensor and AuNPs together, S. aureus can be accurately identified from the common pathogens. This duplex identification system is a promising platform for simple visual identification of S. aureus. Additionally, in the aptasensing process, bacteria are incubated with aptamers and then be removed before the aptamers adding to AuNPs, which may avoid the interactions between bacteria and AuNPs. This strategy can be potentially applied in principle to detect other cells by AuNPs-based aptasensors. PMID:27427591

  6. Cast adrift: Gortex cast liners allow greater patient activity.

    PubMed

    Dubowitz, Gerald; Miller, Deborah M

    2003-01-01

    Extremity fractures are a common injury, with nearly 1.5 million cases reported in the United States in 1998. Treatment often involves lengthy periods of immobilization. This report outlines the use of a Gortex cast liner by a subject who was able to engage in swimming and scuba diving during the healing process. We report that a Gortex cast liner may be considered for an active patient who is keen to return to limited activities during fracture healing. Apparently because of a lack of knowledge of their existence, physicians currently are underutilizing this method of casting in active patients. The use of Gortex liners elsewhere has been reported to have higher patient and physician satisfaction in both use and performance, with no reported detrimental effects on outcome.

  7. Electrochemical study of resistance to localized corrosion of stainless steels for biomaterial applications

    SciTech Connect

    Pan, J.; Karlen, C.; Ulfvin, C.

    2000-03-01

    Sandvik Bioline High-N and 316 LVM are two austenitic stainless steels especially developed for biomaterial applications. Their resistance to localized corrosion was investigated by electrochemical methods including cyclic potentiodynamic polarization and potentiostatic polarization measurements in a phosphate-buffered saline solution and in a simulated crevice solution, i.e., designed for crevice corrosion testing. Sandvik SAF 2507 (a high-performance super duplex stainless steel) was included in the tests as a reference material High-N, higher alloyed than 316 LVM, demonstrated excellent resistance to pitting initiation and a strong tendency to repassivation. High-N proved to have an equivalent or even higher resistance to localized corrosion than SAF 2507. The latter is known for its impressive corrosion properties, particularly in chloride containing environments. While 316 LVM may run the risk of crevice corrosion in implant applications, the risk seems negligible for High-N. In view of the fact that also the mechanical properties are superior to those of 316 LVM, High-N is a very attractive implant material.

  8. Morphological castes in a vertebrate.

    PubMed

    O'Riain, M J; Jarvis, J U; Alexander, R; Buffenstein, R; Peeters, C

    2000-11-21

    Morphological specialization for a specific role has, until now, been assumed to be restricted to social invertebrates. Herein we show that complete physical dimorphism has evolved between reproductives and helpers in the eusocial naked mole-rat. Dimorphism is a consequence of the lumbar vertebrae lengthening after the onset of reproduction in females. This is the only known example of morphological castes in a vertebrate and is distinct from continuous size variation between breeders and helpers in other species of cooperatively breeding vertebrates. The evolution of castes in a mammal and insects represents a striking example of convergent evolution for enhanced fecundity in societies characterized by high reproductive skew. Similarities in the selective environment between naked mole-rats and eusocial insect species highlight the selective conditions under which queen/worker castes are predicted to evolve in animal societies.

  9. METHOD FOR JOINING ALUMINUM TO STAINLESS STEEL

    DOEpatents

    Lemon, L.C.

    1960-05-24

    Aluminum may be joined to stainless steel without the use of flux by tinning the aluminum with a tin solder containing 1% silver and 1% lead, tinning the stainless steel with a 50% lead 50% tin solder, and then sweating the tinned surfaces together.

  10. Energy Consumption of Die Casting Operations

    SciTech Connect

    Jerald Brevick; clark Mount-Campbell; Carroll Mobley

    2004-03-15

    Molten metal processing is inherently energy intensive and roughly 25% of the cost of die-cast products can be traced to some form of energy consumption [1]. The obvious major energy requirements are for melting and holding molten alloy in preparation for casting. The proper selection and maintenance of melting and holding equipment are clearly important factors in minimizing energy consumption in die-casting operations [2]. In addition to energy consumption, furnace selection also influences metal loss due to oxidation, metal quality, and maintenance requirements. Other important factors influencing energy consumption in a die-casting facility include geographic location, alloy(s) cast, starting form of alloy (solid or liquid), overall process flow, casting yield, scrap rate, cycle times, number of shifts per day, days of operation per month, type and size of die-casting form of alloy (solid or liquid), overall process flow, casting yield, scrap rate, cycle times, number of shifts per day, days of operation per month, type and size of die-casting machine, related equipment (robots, trim presses), and downstream processing (machining, plating, assembly, etc.). Each of these factors also may influence the casting quality and productivity of a die-casting enterprise. In a die-casting enterprise, decisions regarding these issues are made frequently and are based on a large number of factors. Therefore, it is not surprising that energy consumption can vary significantly from one die-casting enterprise to the next, and within a single enterprise as function of time.

  11. Casting propellant in rocket engine

    NASA Technical Reports Server (NTRS)

    Roach, J. E.; Froehling, S. C. (Inventor)

    1976-01-01

    A method is described for casting a solid propellant in the casing of a rocket engine having a continuous wall with a single opening which is formed by leaves of a material which melt at a temperature of the propellant and with curved edges concentric to the curvature of the spherical casing. The leaves are inserted into the spherical casing through the opening forming a core having a greater width than the width of the single opening and with curved peripheral edges. The cast propellant forms a solid mass and then heated to melt the leaves and provide a central opening with radial projecting flutes.

  12. Preparation and property of duplex Ni-B-TiO2/Ni nano-composite coatings

    NASA Astrophysics Data System (ADS)

    Wang, Shu-Jen; Wang, Yuxin; Shu, Xin; Tay, Seeleng; Gao, Wei; Shakoor, R. A.; Kahraman, Ramazan

    2015-03-01

    The duplex Nickel-Boron-Titania/Nickel (Ni-B-TiO2/Ni) coatings were deposited on mild steel by using two baths with Ni as the inner layer. TiO2 nanoparticles were incorporated into the Ni-B coatings as the outer layer by using solid particle mixing method. The microstructure, morphology and corrosion resistance of the duplex Ni-B-TiO2/Ni nanocomposite coatings were systemically investigated. The results show that the duplex interface was uniform and the adhesion between two layers was very good. The microhardness of duplex Ni-B-TiO2/Ni coating was much higher than the Ni coating due to the outer layer of Ni-B-TiO2 coating. The corrosion resistance of the duplex Ni-B-TiO2/Ni coating was also significantly improved comparing with single Ni-B coating. The Ni-B-10 g/L TiO2/Ni coating was found to have the best corrosion resistance among these duplex coatings. This type of duplex Ni-B-TiO2/Ni coating, with high hardness and good corrosion resistance properties, should be able to find broad applications under adverse environmental conditions.

  13. Interaction between stainless steel and plutonium metal

    SciTech Connect

    Dunwoody, John T; Mason, Richard E; Freibert, Franz J; Willson, Stephen P; Veirs, Douglas K; Worl, Laura A; Archuleta, Alonso; Conger, Donald J

    2010-01-01

    Long-term storage of excess plutonium is of great concern in the U.S. as well as abroad. The current accepted configuration involves intimate contact between the stored material and an iron-bearing container such as stainless steel. While many safety scenario studies have been conducted and used in the acceptance of stainless steel containers, little information is available on the physical interaction at elevated temperatures between certain forms of stored material and the container itself. The bulk of the safety studies has focused on the ability of a package to keep the primary stainless steel containment below the plutonium-iron eutectic temperature of approximately 410 C. However, the interactions of plutonium metal with stainless steel have been of continuing interest. This paper reports on a scoping study investigating the interaction between stainless steel and plutonium metal in a pseudo diffusion couple at temperatures above the eutectic melt-point.

  14. The comparison of frictional resistance in titanium, self-ligating stainless steel, and stainless steel brackets using stainless steel and TMA archwires: An in vitro study

    PubMed Central

    Khalid, Syed Altaf; Kumar, Vadivel; Jayaram, Prithviraj

    2012-01-01

    Aim: The aim of the study was to compare the frictional resistance of titanium, self-ligating stainless steel, and conventional stainless steel brackets, using stainless steel and titanium molybdenum alloy (TMA) archwires. Materials and Methods: We compared the frictional resistance in 0.018 slot and 0.022 slot of the three brackets – titanium, self-ligating stainless steel, and conventional stainless steel – using stainless steel archwires and TMA archwires. An in vitro study of simulated canine retraction was undertaken to evaluate the difference in frictional resistance between titanium, self-ligating stainless steel, and stainless steel brackets, using stainless steel and TMA archwires. Results and Conclusion: We compared the frictional resistance of titanium, self-ligating stainless steel, and conventional stainless steel brackets, using stainless steel and TMA archwires, with the help of Instron Universal Testing Machine. One-way analysis of variance (ANOVA), Student's “t” test, and post hoc multiple range test at level of <0.05 showed statistically significant difference in the mean values of all groups. Results demonstrated that the titanium, self-ligating stainless steel, and stainless steel brackets of 0.018-inch and 0.022-inch slot had no significant variations in frictional résistance. The self-ligating bracket with TMA archwires showed relatively less frictional resistance compared with the other groups. The titanium bracket with TMA archwires showed relatively less frictional resistance compared with the stainless steel brackets. PMID:23066253

  15. Hybridization accompanying FRET event in labeled natural nucleoside-unnatural nucleoside containing chimeric DNA duplexes.

    PubMed

    Bag, Subhendu Sekhar; Das, Suman K; Pradhan, Manoj Kumar; Jana, Subhashis

    2016-09-01

    Förster resonance energy transfer (FRET) is a highly efficient strategy in illuminating the structures, structural changes and dynamics of DNA, proteins and other biomolecules and thus is being widely utilized in studying such phenomena, in designing molecular/biomolecular probes for monitoring the hybridization event of two single stranded DNA to form duplex, in gene detection and in many other sensory applications in chemistry, biology and material sciences. Moreover, FRET can give information about the positional status of chromophores within the associated biomolecules with much more accuracy than other methods can yield. Toward this end, we want to report here the ability of fluorescent unnatural nucleoside, triazolylphenanthrene ((TPhen)BDo) to show FRET interaction upon hybridization with fluorescently labeled natural nucleosides, (Per)U or (OxoPy)U or (Per)U, forming two stable chimeric DNA duplexes. The pairing selectivity and the thermal duplex stability of the chimeric duplexes are higher than any of the duplexes with natural nucleoside formed. The hybridization results in a Förster resonance energy transfer (FRET) from donor triazolylphenanthrene of (TPhen)BDo to acceptor oxopyrene of (OxoPy)U and/or to perylene chromophore of (Per)U, respectively, in two chimeric DNA duplexes. Therefore, we have established the FRET process in two chimeric DNA duplexes wherein a fluorescently labeled natural nucleoside ((OxoPy)U or (Per)U) paired against an unnatural nucleoside ((TPhen)BDo) without sacrificing the duplex stability and B-DNA conformation. The hybridization accompanying FRET event in these classes of interacting fluorophores is new. Moreover, there is no report of such designed system of chimeric DNA duplex. Our observed phenomenon and the design can potentially be exploited in designing more of such efficient FRET pairs for useful application in the detection and analysis of biomolecular interactions and in material science application. PMID:27498231

  16. The Crystal Structure of Non-Modified and Bipyridine-Modified PNA Duplexes

    SciTech Connect

    Yeh, Joanne I.; Pohl, Ehmke; Truan, Daphne; He, Wei; Sheldrick, George M.; Du, Shoucheng; Achim, Catalina

    2011-09-28

    Peptide nucleic acid (PNA) is a synthetic analogue of DNA that commonly has an N-aminoethyl glycine backbone. The crystal structures of two PNA duplexes, one containing eight standard nucleobase pairs (GGCATGCC)2, and the other containing the same nucleobase pairs and a central pair of bipyridine ligands, have been solved with a resolution of 1.22 and 1.10 {angstrom}, respectively. The non-modified PNA duplex adopts a P-type helical structure similar to that of previously characterized PNAs. The atomic-level resolution of the structures allowed us to observe for the first time specific modes of interaction between the terminal lysines of the PNA and the backbone and the nucleobases situated in the vicinity of the lysines, which are considered an important factor in the induction of a preferred handedness in PNA duplexes. Our results support the notion that whereas PNA typically adopts a P-type helical structure, its flexibility is relatively high. For example, the base-pair rise in the bipyridine-containing PNA is the largest measured to date in a PNA homoduplex. The two bipyridines bulge out of the duplex and are aligned parallel to the major groove of the PNA. In addition, two bipyridines from adjacent PNA duplexes form a p-stacked pair that relates the duplexes within the crystal. The bulging out of the bipyridines causes bending of the PNA duplex, which is in contrast to the structure previously reported for biphenyl-modified DNA duplexes in solution, where the biphenyls are p stacked with adjacent nucleobase pairs and adopt an intrahelical geometry. This difference shows that relatively small perturbations can significantly impact the relative position of nucleobase analogues in nucleic acid duplexes.

  17. Hybridization accompanying FRET event in labeled natural nucleoside-unnatural nucleoside containing chimeric DNA duplexes.

    PubMed

    Bag, Subhendu Sekhar; Das, Suman K; Pradhan, Manoj Kumar; Jana, Subhashis

    2016-09-01

    Förster resonance energy transfer (FRET) is a highly efficient strategy in illuminating the structures, structural changes and dynamics of DNA, proteins and other biomolecules and thus is being widely utilized in studying such phenomena, in designing molecular/biomolecular probes for monitoring the hybridization event of two single stranded DNA to form duplex, in gene detection and in many other sensory applications in chemistry, biology and material sciences. Moreover, FRET can give information about the positional status of chromophores within the associated biomolecules with much more accuracy than other methods can yield. Toward this end, we want to report here the ability of fluorescent unnatural nucleoside, triazolylphenanthrene ((TPhen)BDo) to show FRET interaction upon hybridization with fluorescently labeled natural nucleosides, (Per)U or (OxoPy)U or (Per)U, forming two stable chimeric DNA duplexes. The pairing selectivity and the thermal duplex stability of the chimeric duplexes are higher than any of the duplexes with natural nucleoside formed. The hybridization results in a Förster resonance energy transfer (FRET) from donor triazolylphenanthrene of (TPhen)BDo to acceptor oxopyrene of (OxoPy)U and/or to perylene chromophore of (Per)U, respectively, in two chimeric DNA duplexes. Therefore, we have established the FRET process in two chimeric DNA duplexes wherein a fluorescently labeled natural nucleoside ((OxoPy)U or (Per)U) paired against an unnatural nucleoside ((TPhen)BDo) without sacrificing the duplex stability and B-DNA conformation. The hybridization accompanying FRET event in these classes of interacting fluorophores is new. Moreover, there is no report of such designed system of chimeric DNA duplex. Our observed phenomenon and the design can potentially be exploited in designing more of such efficient FRET pairs for useful application in the detection and analysis of biomolecular interactions and in material science application.

  18. Duplex development and abandonment during evolution of the Lewis thrust system, southern Glacier National Park, Montana

    SciTech Connect

    Yin, An; Kelty, T.K.; Davis, G.A. )

    1989-09-01

    The westernmost duplex (Brave Dog Mountain) includes the low-angle Brave Dog roof fault and Elk Mountain imbricate system, and the easternmost (Rising Wolf Mountain) duplex includes the low-angle Rockwell roof fault and Mt. Henry imbricate system. The geometry of these duplexes suggests that they differ from previously described geometric-kinematic models for duplex development. Their low-angle roof faults were preexisting structures that were locally utilized as roof faults during the formation of the imbricate systems. Crosscutting of the Brave Dog fault by the Mt. Henry imbricate system indicates that the two duplexes formed at different times. The younger Rockwell-Mt. Henry duplex developed 20 km east of the older Brave Dog-Elk Mountain duplex; the roof fault of the former is at a higher structural level. Field relations confirm that the low-angle Rockwell fault existed across the southern Glacier Park area prior to localized formation of the Mt. Henry imbricate thrusts beneath it. These thrusts kinematically link the Rockwell and Lewis faults and may be analogous to P shears that form between two synchronously active faults bounding a simple shear system. The abandonment of one duplex and its replacement by another with a new and higher roof fault may have been caused by (1) warping of the older and lower Brave Dog roof fault during the formation of the imbricate system (Elk Mountain) beneath it, (2) an upward shifting of the highest level of a simple shear system in the Lewis plate to a new decollement level in subhorizontal belt strata (= the Rockwell fault) that lay above inclined strata within the first duplex, and (3) a reinitiation of P-shear development (= Mt. Henry imbricate faults) between the Lewis thrust and the subparallel, synkinematic Rockwell fault.

  19. Development of New Stainless Steel

    SciTech Connect

    Robert F. Buck

    2005-08-30

    A new family of innovative martensitic stainless steels, 521-A, 521-B, and 521-C has been developed by Advanced Steel Technology, LLC (Trafford, PA) as high strength fastener (bolt) materials for use at moderate temperatures in turbine engines, including steam turbines, gas turbines, and aircraft engines. The primary objective of the development program was to create a martensitic stainless steel with high strength at moderate temperatures, and which could replace the expensive nickel-based superalloy IN 718 in some fasteners applications. A secondary objective was to replace conventional 12Cr steels such as AISI 422 used as blades, buckets and shafts that operate at intermediate temperatures in turbine engines with stronger steel. The composition of the new alloys was specifically designed to produce excellent mechanical properties while integrating heat treatment steps into production to reduce energy consumption during manufacturing. As a result, production costs and energy consumption during production of rolled bar products is significantly lower than conventional materials. Successful commercialization of the new alloys would permit the installed cost of certain turbine engines to be reduced without sacrificing high availability or operational flexibility, thereby enhancing the global competitiveness of U.S. turbine engine manufacturers. Moreover, the domestic specialty steel industry would also benefit through increased productivity and reduced operating costs, while increasing their share of the international market for turbine engine fasteners, blades, buckets and shafts.

  20. INTERIOR VIEW WITH CASTING MACHINE AND A 4' DUCTILE IRON ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW WITH CASTING MACHINE AND A 4' DUCTILE IRON PIPE BEING CENTRIFUGALLY CAST, AS OPERATOR WATCHES TO ENSURE QUALITY. - McWane Cast Iron Pipe Company, Pipe Casting Area, 1201 Vanderbilt Road, Birmingham, Jefferson County, AL

  1. INTERIOR VIEW OF CASTING MACHINE WITH 4' DUCTILE IRON PIPE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW OF CASTING MACHINE WITH 4' DUCTILE IRON PIPE BEING WEIGHED ON SCALES AT CASTING MACHINE. - McWane Cast Iron Pipe Company, Pipe Casting Area, 1201 Vanderbilt Road, Birmingham, Jefferson County, AL

  2. INTERIOR VIEW WITH CASTING MACHINE AND A 4" DUCTILE IRON ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW WITH CASTING MACHINE AND A 4" DUCTILE IRON PIPE BEING EXTRACTED FROM CASTING MACHINE - McWane Cast Iron Pipe Company, Pipe Casting Area, 1201 Vanderbilt Road, Birmingham, Jefferson County, AL

  3. INTERIOR VIEW WITH CASTING MACHINE COOLING A 20' IRON PIPE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW WITH CASTING MACHINE COOLING A 20' IRON PIPE PRIOR TO EXTRACTION FROM CASTING MACHINE. - McWane Cast Iron Pipe Company, Pipe Casting Area, 1201 Vanderbilt Road, Birmingham, Jefferson County, AL

  4. Geometry of an outcrop-scale duplex in Devonian flysch, Maine

    USGS Publications Warehouse

    Bradley, D.C.; Bradley, L.M.

    1994-01-01

    We describe an outcrop-scale duplex consisting of 211 exposed repetitions of a single bed. The duplex marks an early Acadian (Middle Devonian) oblique thrust zone in the Lower Devonian flysch of northern Maine. Detailed mapping at a scale of 1:8 has enabled us to measure accurately parameters such as horse length and thickness, ramp angles and displacements; we compare these and derivative values with those of published descriptions of duplexes, and with theoretical models. Shortening estimates based on line balancing are consistently smaller than two methods of area balancing, suggesting that layer-parallel shortening preceded thrusting. ?? 1994.

  5. Nucleic acid duplexes incorporating a dissociable covalent base pair

    NASA Technical Reports Server (NTRS)

    Gao, K.; Orgel, L. E.; Bada, J. L. (Principal Investigator)

    1999-01-01

    We have used molecular modeling techniques to design a dissociable covalently bonded base pair that can replace a Watson-Crick base pair in a nucleic acid with minimal distortion of the structure of the double helix. We introduced this base pair into a potential precursor of a nucleic acid double helix by chemical synthesis and have demonstrated efficient nonenzymatic template-directed ligation of the free hydroxyl groups of the base pair with appropriate short oligonucleotides. The nonenzymatic ligation reactions, which are characteristic of base paired nucleic acid structures, are abolished when the covalent base pair is reduced and becomes noncoplanar. This suggests that the covalent base pair linking the two strands in the duplex is compatible with a minimally distorted nucleic acid double-helical structure.

  6. The sequence dependence of circular dichroism spectra of DNA duplexes.

    PubMed

    Arnott, S; Arnott, S

    1975-09-01

    The three satellite DNAs of Drosophila virilis, that approximate to poly d(CAAACTA)-poly d(TAGTTTG), poly d(TAAACTA)-poly d(TAGTTTA), poly d(CAAATTA)-poly d(TAATTTG), the satellite DNA of Drosophila melanogaster that approximates to poly d(AATAT)-poly d(ATATT), the synthetic DNA duplexes, poly dG-poly dC, poly d(AT)-poly d(AT), poly d(AAT)-poly d(ATT), poly d(AAC)-poly d(GTT), poly d(TAC)-poly d(GTA) and the block copolymer d(C15A15)-d(T15G15) all have circular dichroism spectra consistent with the propositions that they have the same molecular geometry in solution and that it is the kind and frequency of nucleotide triplet sequences that determines their spectral characteristics. Poly dA-poly dT is apparently an exception.

  7. Pyrazinetetracarboxamide: A Duplex Ligand for Palladium(II).

    PubMed

    Lohrman, Jessica; Telikepalli, Hanumaiah; Johnson, Thomas S; Jackson, Timothy A; Day, Victor W; Bowman-James, Kristin

    2016-06-01

    Tetraethylpyrazine-2,3,5,6-tetracarboxamide forms a dipalladium(II) complex with acetates occupying the fourth coordination sites of the two bound metal ions. Crystallographic results indicate that the "duplex" dipincer has captured two protons that serve as the counterions. The protons lie between adjacent amide carbonyl groups with very short O···O distances of 2.435(5) Å. In the free base, the adjacent carbonyl groups are farther apart, averaging 3.196(3) Å. While the dipalladium(II) complexes stack in an ordered stepwise fashion along the a axis, the free base molecules stack on top of each other, with each pincer rotated by about 60° from the one below. PMID:27187158

  8. Isothermal DNA amplification strategies for duplex microorganism detection.

    PubMed

    Santiago-Felipe, Sara; Tortajada-Genaro, Luis Antonio; Morais, Sergi; Puchades, Rosa; Maquieira, Ángel

    2015-05-01

    A valid solution for micro-analytical systems is the selection of a compatible amplification reaction with a simple, highly-integrated efficient design that allows the detection of multiple genomic targets. Two approaches under isothermal conditions are presented: recombinase polymerase amplification (RPA) and multiple displacement amplification (MDA). Both methods were applied to a duplex assay specific for Salmonella spp. and Cronobacter spp., with excellent amplification yields (0.2-8.6 · 10(8) fold). The proposed approaches were successfully compared to conventional PCR and tested for the milk sample analysis as a microarray format on a compact disc (support and driver). Satisfactory results were obtained in terms of resistance to inhibition, selectivity, sensitivity (10(1)-10(2)CFU/mL) and reproducibility (below 12.5%). The methods studied are efficient and cost-effective, with a high potential to automate microorganisms detection by integrated analytical systems working at a constant low temperature.

  9. Nucleic acid duplexes incorporating a dissociable covalent base pair.

    PubMed

    Gao, K; Orgel, L E

    1999-12-21

    We have used molecular modeling techniques to design a dissociable covalently bonded base pair that can replace a Watson-Crick base pair in a nucleic acid with minimal distortion of the structure of the double helix. We introduced this base pair into a potential precursor of a nucleic acid double helix by chemical synthesis and have demonstrated efficient nonenzymatic template-directed ligation of the free hydroxyl groups of the base pair with appropriate short oligonucleotides. The nonenzymatic ligation reactions, which are characteristic of base paired nucleic acid structures, are abolished when the covalent base pair is reduced and becomes noncoplanar. This suggests that the covalent base pair linking the two strands in the duplex is compatible with a minimally distorted nucleic acid double-helical structure. PMID:10611299

  10. Advanced Lost Foam Casting Technology

    SciTech Connect

    Charles E. Bates; Harry E. Littleton; Don Askeland; Taras Molibog; Jason Hopper; Ben Vatankhah

    2000-11-30

    This report describes the research done under the six tasks to improve the process and make it more functional in an industrial environment. Task 1: Pattern Pyrolysis Products and Pattern Properties Task 2: Coating Quality Control Task 3: Fill and Solidification Code Task 4: Alternate Pattern Materials Task 5: Casting Distortion Task 6: Technology Transfer

  11. Casting Freedom, 1860-1862

    ERIC Educational Resources Information Center

    Social Education, 2005

    2005-01-01

    Thomas Crawford, an American Sculptor, created the full-size figure of Freedom in clay. Molds were made, from which a full-size positive plaster model was cast in five main sections. This model is on view today in the basement rotunda of the Russell Senate Office Building. Clark Mills was a self-taught American sculptor with experience in casting…

  12. Tape casting of magnesium oxide.

    SciTech Connect

    Ayala, Alicia; Corral, Erica L.; Loehman, Ronald E.; Bencoe, Denise Nora; Reiterer, Markus; Shah, Raja A.

    2008-02-01

    A tape casting procedure for fabricating ceramic magnesium oxide tapes has been developed as a method to produce flat sheets of sintered MgO that are thin and porous. Thickness of single layer tapes is in the range of 200-400 {micro}m with corresponding surface roughness values in the range of 10-20 {micro}m as measured by laser profilometry. Development of the tape casting technique required optimization of pretreatment for the starting magnesium oxide (MgO) powder as well as a detailed study of the casting slurry preparation and subsequent heat treatments for sintering and final tape flattening. Milling time of the ceramic powder, plasticizer, and binder mixture was identified as a primary factor affecting surface morphology of the tapes. In general, longer milling times resulted in green tapes with a noticeably smoother surface. This work demonstrates that meticulous control of the entire tape casting operation is necessary to obtain high-quality MgO tapes.

  13. Molding A Cast Metals Program

    ERIC Educational Resources Information Center

    Trumble, Dale E.

    1975-01-01

    The cast metals program, a two-year associate degree program, at Muskegon Community College, Musegon, Michigan operates in close cooperation with the local foundry industry to provide a background for entry-level technical jobs and for continued studies toward a four-year degree. (EA)

  14. Graphite Formation in Cast Iron

    NASA Technical Reports Server (NTRS)

    Stefanescu, D. M.

    1985-01-01

    In the first phase of the project it was proven that by changing the ratio between the thermal gradient and the growth rate for commercial cast iron samples solidifying in a Bridgman type furnace, it is possible to produce all types of graphite structures, from flake to spheroidal, and all types of matrices, from ferritic to white at a certain given level of cerium. KC-135 flight experiments have shown that in a low-gravity environment, no flotation occurs even in spheroidal graphite cast irons with carbon equivalent as high as 5%, while extensive graphite flotation occurred in both flake and spheroidal graphite cast irons, in high carbon samples solidified in a high gravity environment. This opens the way for production of iron-carbon composite materials, with high carbon content (e.g., 10%) in a low gravity environment. By using KC-135 flights, the influence of some basic elements on the solidification of cast iron will be studied. The mechanism of flake to spheroidal graphite transition will be studied, by using quenching experiments at both low and one gravity for different G/R ratios.

  15. Math: Objectives Guide. Project CAST.

    ERIC Educational Resources Information Center

    Charles County Board of Education, La Plata, MD. Office of Special Education.

    The guide lists math objectives needed for independent living by secondary special education students. One of a series of Project CAST (Community and School Together) life skills manuals, the guide outlines basic competencies in terms of goal statements, behavioral objectives, and specialized vocabulary for the following areas: money, making…

  16. Prediction of Microporosity in Shrouded Impeller Castings

    SciTech Connect

    Viswanathan, S. Nelson, C.D.

    1998-09-01

    The purpose of this Cooperative Research and Development Agreement (CRADA) between the Oak Ridge National Laboratory (ORNL) and Morris Bean and Company was to link computer models of heat and fluid flow with previously developed quality criteria for the prediction of microporosity in a Al-4.5% Cu alloy shrouded impeller casting. The results may be used to analyze the casting process design for the commercial production of 206 o alloy shrouded impeller castings. Test impeller castings were poured in the laboratory for the purpose of obtaining thermal data and porosity distributions. Also, a simulation of the test impeller casting was conducted and the results validated with porosity measurements on the test castings. A comparison of the predicted and measured microporosity distributions indicated an excellent correlation between experiments and prediction. The results of the experimental and modeling studies undertaken in this project indicate that the quality criteria developed for the prediction of microporosity in Al-4.5% Cu alloy castings can accurately predict regions of elevated microporosity even in complex castings such as the shrouded impeller casting. Accordingly, it should be possible to use quality criteria for porosity prediction in conjunction with computer models of heat and fluid flow to optimize the casting process for the production of shrouded impeller castings. Since high levels of microporosity may be expected to result in poor fatigue properties, casting designs that are optimized for low levels of microporosity should exhibit superior fatigue life.

  17. 14 CFR 27.621 - Casting factors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Casting factors. 27.621 Section 27.621... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction General § 27.621 Casting factors. (a) General... approved specifications. Paragraphs (c) and (d) of this section apply to structural castings...

  18. 14 CFR 27.621 - Casting factors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Casting factors. 27.621 Section 27.621... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction General § 27.621 Casting factors. (a) General... approved specifications. Paragraphs (c) and (d) of this section apply to structural castings...

  19. 14 CFR 29.621 - Casting factors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Casting factors. 29.621 Section 29.621... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction General § 29.621 Casting factors. (a... approved specifications. Paragraphs (c) and (d) of this section apply to structural castings...

  20. 14 CFR 27.621 - Casting factors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Casting factors. 27.621 Section 27.621... STANDARDS: NORMAL CATEGORY ROTORCRAFT Design and Construction General § 27.621 Casting factors. (a) General... approved specifications. Paragraphs (c) and (d) of this section apply to structural castings...

  1. 14 CFR 29.621 - Casting factors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Casting factors. 29.621 Section 29.621... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction General § 29.621 Casting factors. (a... approved specifications. Paragraphs (c) and (d) of this section apply to structural castings...

  2. 14 CFR 29.621 - Casting factors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Casting factors. 29.621 Section 29.621... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Design and Construction General § 29.621 Casting factors. (a... approved specifications. Paragraphs (c) and (d) of this section apply to structural castings...

  3. Chimerical categories: caste, race, and genetics.

    PubMed

    Sabir, Sharjeel

    2003-12-01

    Is discrimination based on caste equivalent to racism? This paper explores the complex relationship between genetic, race and caste. It also discusses the debate over the exclusion of a discussion of caste-based discrimination at the 2001 World Conference against Racism, Racial Discrimination, Xenophobia and Related Intolerance held in Durban, South Africa.

  4. Duplex Doppler ultrasound study of the temporomandibular joint.

    PubMed

    Stagnitti, A; Marini, A; Impara, L; Drudi, F M; Lo Mele, L; Lillo Odoardi, G

    2012-06-01

    Sommario INTRODUZIONE: La fisiologia articolare dell’articolazione temporo-mandibolare (ATM) può essere esaminata sia dal punto di vista clinico che strumentale. La diagnostica per immagini ha da tempo contribuito con la risonanza magnetica (RM) e anche con la radiografia (Rx) e la tomografia computerizzata (TC) all’analisi della morfologia dei capi articolari e della cinetica condilare. L’esame duplex-ecodoppler è una metodica di largo impiego nello studio delle strutture in movimento in particolar modo a livello delle strutture del sistema vascolare. MATERIALI E METODI: È stata utilizzata un’apparecchiatura Toshiba APLIO SSA-770A, con l’uso di tecnica duplex-ecodoppler multi display, che consente la visualizzazione contemporanea dell’immagine ecografica e dei segnali Doppler utilizzando una sonda lineare del tipo phased array con cristalli trasduttori funzionanti ad una frequenza fondamentale di 6 MHz per gli spettri Doppler pulsati e 7.5 MHz per l’imaging ecografico. Sono stati esaminati nel Dipartimento di Scienze Radiologiche, Oncologiche e Anatomo-patologiche dell’Università “Sapienza” di Roma, 30 pazienti del reparto di Ortognatodonzia dell’Istituto di Odontoiatria della stessa Università. RISULTATI: Nei pazienti normali si è ottenuta un’alternanza regolare degli spettri Doppler, mentre nei soggetti con disfunzioni del complesso condilo-meniscale, si è persa la regolarità della sommatoria degli spettri di Fourier, con altezze incostanti in relazione a spostamenti irregolari del complesso condilo-meniscale. CONCLUSIONI: L’esame ecodoppler si è dimostrato, in tutti i pazienti, capace di discriminare quelli normali dai patologici e tra questi ultimi ha permesso di identificare gli aspetti più significativi delle patologie disfunzionali.

  5. Microstructural development in waste form alloys cast from irradiated cladding residual from the electrometallurgical treatment of EBR-II spent fuel.

    SciTech Connect

    Keiser, D. D., Jr.

    1999-06-10

    A metallic waste form alloy that consists primarily of stainless steel and zirconium is being developed by Argonne National Laboratory to contain metallic waste constituents that are residual from an electrometallurgical treatment process for spent nuclear fuel. Ingots have been cast in an induction furnace in a hot cell using actual, leftover, irradiated, EBR-II cladding hulls treated in an electrorefiner. The as-cast ingots have been sampled using a core-drilling and an injection-casting technique. In turn, generated samples have been characterized using chemical analysis techniques and a scanning electron microscope equipped with energy dispersive and wavelength-dispersive spectrometers. As-cast ingots contain the predicted concentration levels of the various constituents, and most of the phases that develop are analogous to those for alloys generated using non-radioactive surrogates for the various fission products.

  6. Active wear and failure mechanisms of TiN-coated high speed steel and TiN-coated cemented carbide tools when machining powder metallurgically made stainless steels

    SciTech Connect

    Jiang, L.; Haenninen, H.; Paro, J.; Kauppinen, V.

    1996-09-01

    In this study, active wear and failure mechanisms of both TiN-coated high speed steel and TiN-coated cemented carbide tools when machining stainless steels made by powder metallurgy in low and high cutting speed ranges, respectively, have been investigated. Abrasive wear mechanisms, fatigue-induced failure, and adhesive and diffusion wear mechanisms mainly affected the tool life of TiN-coated high speed steel tools at cutting speeds below 35 m/min, between 35 and 45 m/min, and over 45 m/min, respectively. Additionally, fatigue-induced failure was active at cutting speeds over 45 m/min in the low cutting speed range when machining powder metallurgically made duplex stainless steel 2205 and austenitic stainless steel 316L. In the high cutting speed range, from 100 to 250 m/min, fatigue-induced failure together with diffusion wear mechanism, affected the tool life of TiN-coated cemented carbide tools when machining both 316L and 2205 stainless steels. It was noticed that the tool life of TiN-coated high speed steel tools used in the low cutting speed range when machining 2205 steel was longer than that when machining 316L steel, whereas the tool life of TiN-coated cemented carbide tools used in the high cutting speed range when machining 316L steel was longer than that when machining 2205 steel.

  7. Diabetic Neuropathy: What is a Total Contact Cast?

    MedlinePlus

    ... Web version Diabetic Neuropathy | What is a Total Contact Cast? What is a total contact cast? A total contact cast is a cast used to treat ulcers ( ... foot--that's why it is called a total contact cast. The cast helps to protect the skin ...

  8. Electron backscatter diffraction study of deformation and recrystallization textures of individual phases in a cross-rolled duplex steel

    SciTech Connect

    Zaid, Md; Bhattacharjee, P.P.

    2014-10-15

    The evolution of microstructure and texture during cross-rolling and annealing was investigated by electron backscatter diffraction in a ferritic–austenitic duplex stainless steel. For this purpose an alloy with nearly equal volume fraction of the two phases was deformed by multi-pass cross-rolling process up to 90% reduction in thickness. The rolling and transverse directions were mutually interchanged in each pass by rotating the sample by 90° around the normal direction. In order to avoid deformation induced phase transformation and dynamic strain aging, the rolling was carried out at an optimized temperature of 898 K (625 °C) at the warm-deformation range. The microstructure after cross warm-rolling revealed a lamellar structure with alternate arrangement of the bands of two phases. Strong brass and rotated brass components were observed in austenite in the steel after processing by cross warm-rolling. The ferrite in the cross warm-rolling processed steel showed remarkably strong RD-fiber (RD//< 011 >) component (001)< 011 >. The development of texture in the two phases after processing by cross warm-rolling could be explained by the stability of the texture components. During isothermal annealing of the 90% cross warm-rolling processed material the lamellar morphology was retained before collapse of the lamellar structure to the mutual interpenetration of the phase bands. Ferrite showed recovery resulting in annealing texture similar to the deformation texture. In contrast, the austenite showed primary recrystallization without preferential orientation selection leading to the retention of deformation texture. The evolution of deformation and annealing texture in the two phases of the steel was independent of one another. - Highlights: • Effect of cross warm-rolling on texture formation is studied in duplex steel. • Brass texture in austenite and (001)<110 > in ferrite are developed. • Ferrite shows recovery during annealing retaining the (001

  9. Prototype casting fabrication by stereolithography

    SciTech Connect

    Cromwell, W.E.

    1990-11-01

    A new product development technology is emerging which could have a major impact on the investment casting industry. It's identified by several names, the most common of which is STEREOLITHOGRAPHY.'' This technology involves a three-dimensional printing process which will yield plastic parts (polymer models) from solid, surface, or wireframe CAD files. The concept links a CAD database to a process which guides a laser beam to solidify liquid photo-curable polymer into a programmed shaped. The process can produce models in far less time and at far less cost than can be done by other known (conventional) model producing methods. Parts that would normally require weeks or months to prototype with conventional processes can be produced in a matter of hours by Stereolithography. The Allied-Signal Inc., Kansas City Division, is engaged in a development project (funded by the Department of Energy) which is aimed at establishing this process as a practical, expedient, and cost-effective method fabricating prototype investment castings. The early phases of the project include procurement of a special designed test unit for several companies (Service Centers) involved in fabrication of models. These models are produced in various materials and used in experimental casting programs being conducted with four casting suppliers (two ferrous and two non-ferrous). This presentation will cover the objectives of the project and the results obtained up to this time. We will also briefly review future plans for the continuation of the project, until this new technology has been proven as a viable process for rapid development of investment castings.

  10. Interfacial Phenomena in Fe/Stainless Steel-TiC Systems and the Effect of Mo

    NASA Astrophysics Data System (ADS)

    Kiviö, Miia; Holappa, Lauri; Yoshikawa, Takeshi; Tanaka, Toshihiro

    2014-12-01

    Titanium carbide is used as reinforcement particles in composites due to its hardness, wear resistance and stability. This work is a part of the study in which titanium carbides are formed in stainless steel castings in the mold to improve the wear resistance of a certain surface of the casting. Such local reinforcement is a very potential method but it is a quite demanding task requiring profound knowledge of interfacial phenomena in the system, wettability, stability, dissolution and precipitation of new phases in production of these materials. Good wetting between different constituents in the material is a key factor to attain maximal positive effects. Mo is used with TiC or Ti(C,N) reinforcement in composites to improve wettability. In this work the effect of Mo on the phenomena in Fe/stainless steel-TiC systems was examined by wetting experiments between the substrate and the alloy. Wetting was not significantly improved by adding Mo to the systems. Core-rim type carbides as well as more homogenous carbide particles were observed. Overall the carbide particles are very complex regarding to their chemistry, size and shape which aspects have to be taken into account in the development of these materials and manufacturing processes.

  11. Land-based turbine casting initiative

    SciTech Connect

    Mueller, B.A.; Spicer, R.A.

    1995-12-31

    To meet goals for the ATS program, technical advances developed for aircraft gas turbine engines need to be applied to land-based gas turbines. These advances include directionally solidified and single crystal castings, alloys tailored to exploit these microstructures, complex internal cooling schemes, and coatings. The proposed program to scale aircraft gas turbine casting technology up to land based gas turbine size components is based on low sulfur alloys, casting process development, post-cast process development, and establishing casting defect tolerance levels. The inspection side is also discussed.

  12. Tritiated Water Interaction with Stainless Steel

    SciTech Connect

    Glen R. Longhurst

    2007-05-01

    Experiments conducted to study tritium permeation of stainless steel at ambient and elevated temperatures revealed that HT converts relatively quickly to HTO. Further, the HTO partial pressure contributes essentially equally with elemental tritium gas in driving permeation through the stainless steel. Such permeation appears to be due to dissociation of the water molecule on the hot stainless steel surface. There is an equilibrium concentration of HTO vapor above adsorbed gas on the walls of the experimental apparatus evident from freezing transients. The uptake process of tritium from the carrier gas involves both surface adsorption and isotopic exchange with surface bound water.

  13. Rapid method to detect duplex formation in sequencing by hybridization methods

    DOEpatents

    Mirzabekov, A.D.; Timofeev, E.N.; Florentiev, V.L.; Kirillov, E.V.

    1999-01-19

    A method for determining the existence of duplexes of oligonucleotide complementary molecules is provided. A plurality of immobilized oligonucleotide molecules, each of a specific length and each having a specific base sequence, is contacted with complementary, single stranded oligonucleotide molecules to form a duplex. Each duplex facilitates intercalation of a fluorescent dye between the base planes of the duplex. The invention also provides for a method for constructing oligonucleotide matrices comprising confining light sensitive fluid to a surface and exposing the light-sensitive fluid to a light pattern. This causes the fluid exposed to the light to coalesce into discrete units and adhere to the surface. This places each of the units in contact with a set of different oligonucleotide molecules so as to allow the molecules to disperse into the units. 13 figs.

  14. Electrochemical Investigation of Interaction between a Bifunctional Probe and GG Mismatch Duplex.

    PubMed

    Li, Jiao; He, Hanping; Peng, Xiaoqian; Huang, Min; Zhang, Xiuhua; Wang, Shengfu

    2015-01-01

    A bifunctional probe (FecNC), containing a recognition part and an electrochemical active center, was applied to electrochemical detection of GG mismatch duplexes. The preparation of gold electrodes modified by mismatch and complementatry duplexes was characterized by electrochemical impedance spectroscopy (EIS) and optimized for better detection in terms of self-assembly time, hybridization time, and incubation time. The interaction between FecNC and DNA duplexes modified on the surface of a gold electrode was explored by square wave voltammetry (SWV) and EIS. The results showed that the DNA duplexes with GG mismatch on the surface of a gold electrode was easily detected by the largest electrochemical signal of the bifunctional probe because of its selective binding to GG mismatches. The bifunctional probe could offer a simple, effective electrochemical detection of GG mismatches, and theoretical bases for development of electrochemical biosensors. Further, the method would be favorable for diagnosis of genetic diseases. PMID:26165289

  15. Electrochemical Investigation of Interaction between a Bifunctional Probe and GG Mismatch Duplex.

    PubMed

    Li, Jiao; He, Hanping; Peng, Xiaoqian; Huang, Min; Zhang, Xiuhua; Wang, Shengfu

    2015-01-01

    A bifunctional probe (FecNC), containing a recognition part and an electrochemical active center, was applied to electrochemical detection of GG mismatch duplexes. The preparation of gold electrodes modified by mismatch and complementatry duplexes was characterized by electrochemical impedance spectroscopy (EIS) and optimized for better detection in terms of self-assembly time, hybridization time, and incubation time. The interaction between FecNC and DNA duplexes modified on the surface of a gold electrode was explored by square wave voltammetry (SWV) and EIS. The results showed that the DNA duplexes with GG mismatch on the surface of a gold electrode was easily detected by the largest electrochemical signal of the bifunctional probe because of its selective binding to GG mismatches. The bifunctional probe could offer a simple, effective electrochemical detection of GG mismatches, and theoretical bases for development of electrochemical biosensors. Further, the method would be favorable for diagnosis of genetic diseases.

  16. Replication of linear duplex DNA in vitro with bacteriophage T5 DNA polymerase

    SciTech Connect

    Fujimura, R. K.; Das, S. K.; Allison, D. P.; Roop, B. C.

    1980-01-01

    Two sets of experiments are presented that attempt to contribute to understanding the mechanisms of DNA replication. The specific areas discussed are fidelity of DNA replication and initiation of replication of duplex DNA. (ACR)

  17. Two-flux transfer matrix model for predicting the reflectance and transmittance of duplex halftone prints.

    PubMed

    Mazauric, Serge; Hébert, Mathieu; Simonot, Lionel; Fournel, Thierry

    2014-12-01

    We introduce a model allowing convenient calculation of the spectral reflectance and transmittance of duplex prints. It is based on flux transfer matrices and enables retrieving classical Kubelka-Munk formulas, as well as extended formulas for nonsymmetric layers. By making different assumptions on the flux transfers, we obtain two predictive models for the duplex halftone prints: the "duplex Clapper-Yule model," which is an extension of the classical Clapper-Yule model, and the "duplex primary reflectance-transmittance model." The two models can be calibrated from either reflectance or transmittance measurements; only the second model can be calibrated from both measurements, thus giving optimal accuracy for both reflectance and transmittance predictions. The conceptual differences between the two models are deeply analyzed, as well as their advantages and drawbacks in terms of calibration. According to the test carried out in this study with paper printed in inkjet, their predictive performances are good provided appropriate calibration options are selected.

  18. Gating geometry studies of thin-walled 17-4PH investment castings

    SciTech Connect

    Maguire, M.C.; Zanner, F.J.

    1992-01-01

    The ability to design gating systems that reliably feed and support investment castings is often the result of cut-and-try'' methodology. Factors such as hot tearing, porosity, cold shuts, misruns, and shrink are defects often corrected by several empirical gating design iterations. Sandia National Laboratories is developing rules that aid in removing the uncertainty involved in the design of gating systems for investment castings. In this work, gating geometries used for filling of thin walled investment cast 17-4PH stainless steel flat plates were investigated. A full factorial experiment evaluating the influence of metal pour temperature, mold preheat temperature, and mold channel thickness were conducted for orientations that filled a horizontal flat plate from the edge. A single wedge gate geometry was used for the edge-gated configuration. Thermocouples placed along the top of the mold recorded metal front temperatures, and a real-time x-ray imaging system tracked the fluid flow behavior during filling of the casting. Data from these experiments were used to determine the terminal fill volumes and terminal fill times for each gate design.

  19. Gating geometry studies of thin-walled 17-4PH investment castings

    SciTech Connect

    Maguire, M.C.; Zanner, F.J.

    1992-11-01

    The ability to design gating systems that reliably feed and support investment castings is often the result of ``cut-and-try`` methodology. Factors such as hot tearing, porosity, cold shuts, misruns, and shrink are defects often corrected by several empirical gating design iterations. Sandia National Laboratories is developing rules that aid in removing the uncertainty involved in the design of gating systems for investment castings. In this work, gating geometries used for filling of thin walled investment cast 17-4PH stainless steel flat plates were investigated. A full factorial experiment evaluating the influence of metal pour temperature, mold preheat temperature, and mold channel thickness were conducted for orientations that filled a horizontal flat plate from the edge. A single wedge gate geometry was used for the edge-gated configuration. Thermocouples placed along the top of the mold recorded metal front temperatures, and a real-time x-ray imaging system tracked the fluid flow behavior during filling of the casting. Data from these experiments were used to determine the terminal fill volumes and terminal fill times for each gate design.

  20. Dimensional Accuracy of Stone Casts Obtained with Multiple Pours into the Same Mold

    PubMed Central

    Valente, Valdimar da Silva; Zanetti, Artêmio Luiz; Feltrin, Pedro Paulo; Inoue, Ricardo Tatsuo; de Moura, Carmem Dolores Vilarinho Soares; Pádua, Luiz Evaldo de Moura

    2012-01-01

    Aim. The aim of the present study was to compare the dimensional accuracy of stone casts obtained with vinyl polysiloxane molds through the double-impression technique with three pours into the same mold. Methods. A stainless steel master model was constructed simulating a three-unit fixed prosthesis. Twelve impressions were taken of this master model with addition silicone, using the double-impression technique. Three pours of type IV gypsum were then made into each mold, thus producing 36 casts. The pours were made 1 hour, 6 hours and 24 hours after the impression procedure. Next, intra- and interabutment measurements were made in a coordinate measuring machine. Results. Comparative analysis of the dimensional accuracy of stone casts resulting from multiple pours was not statistically significant in pours first and second (P > 0.05). These values, however, were statistically significant at third pour in the height in abutment 1 and upper distance interabutment. Conclusion. The wait time (1 hour, and 6 hours) observed before pouring the stone into the same molds did not cause significant dimensional accuracy of the casts. PMID:23320186